DECIMAL NUMBERS

1. Learning to Solve DECIMAL NUMBERS (Modular Workbook for Grade VI) Student Researchers/ Authors: PAMN FAYE HAZEL M. VALIN RON ANGELO A. DRONA ASST. PROF. BEATRIZ P. RAYMUNDO Module Consultant MR. FOR – IAN V. SANDOVAL Module Adviser Contents 7 8 1 04 3 6 90 5

2. L aguna u p s tate olytechnic niversity VMGOs Content Next

3. A premier university in CALABARZON, offering academic programs and related services designed to respond to the requirements of the Philippines and the global economy, particularly, Asian countries. Vision Next Back

4. The University shall primarily provide advanced education, professional, technological and vocational instruction in agriculture, fisheries, forestry, science, engineering, industrial technologies, teacher education, medicine, law, arts and sciences, information technology and other related fields. It shall also undertake research and extension services, and provide a progressive leadership in its areas of specialization. Mission Next Back

5. In pursuit of college mission/vision the college of education is committed to develop the full potential of the individuals and equip them with knowledge, skills and attitudes in teacher education allied fields effectively responds to the increasing demands, challenge and opportunities of changing time for global competitiveness. Goals of College of Education Next Back

6. Objectives of Bachelor of Elementary Education 1. Produce graduates who can demonstrate and practice the professional and ethical requirements for the Bachelor of Elementary Education such as: 2. Acquire basic and major trainings in Bachelor of Elementary Education focusing on General Education and Pre - School Education. 3. Produce mentors who are knowledgeable and skilled in teaching pre - school learners and elementary grades and with desirable values and attitudes or efficiency and effectiveness. 4. Conduct research and development in teacher education and other related fields. 5. Extend services and other related activities for the advancement of community life. Content Back

7. Foreword Content Next

8. This Teacher’s Guide Module entitled “Learning to Solve Decimal Numbers (Modular Workbook for Grade VI)” is part of the requirements in Educational Technology 2 under the revised curriculum for Bachelor in Secondary Education based on CHED Memorandum Order (CMO)-30, Series of 2004. Educational Technology 2 is a three (3)-unit course designed to introduce both traditional and innovative technologies to facilitate and foster meaningful and effective learning where students are expected to demonstrate a sound understanding of the nature, application and production of the various types of educational technologies. Next Back

9. The students are provided with guidance and assistance of selected faculty members of the university through the selection, production and utilization of appropriate technology tools in developing technology-based teacher support materials. Through the role and functions of computers especially the Internet, the student researchers and the advisers are able to design and develop various types of alternative delivery systems. These kind of activities offer a remarkable learning experience for the education students as future mentors especially in the preparation of instructional materials. Next Back

10. The output of the group’s effort may serve as an educational research of the institution in providing effective and quality education. The lessons and evaluations presented in this module may also function as a supplementary reference for secondary teachers and students. Back Next

11. FOR-IAN V. SANDOVAL Computer Instructor / Adviser Educational Technology 2 BEATRIZ P. RAYMUNDO Assistant Professor II / Consultant LYDIA R. CHAVEZ Dean College of Education Content Back

12. Preface Content Next

13. This instructional modular workbook entitled “Learning to Solve Decimal Numbers (Modular Workbook for Grade VI)”, which geared toward the objective of making quality education available to all and offers you a very interesting and helpful friend in your journey to the world of decimal numbers. Dear Learners, Back Next

14. This modular workbook offers you many experiences in learning decimal numbers. This time, you will study how to read, write, and name decimal numbers and how to compare order and round off decimal numbers. Of course you will also express the equivalent fractions and decimals. Back Next

15. You will also experience the four (4) fundamental operations (Addition, Subtraction, Multiplication and Division) dealing with decimal numbers. Lastly, you will also solve more difficult problems involving the four (4) fundamental operations using decimal numbers. Learning decimal content is much more skillful in drilling with the application of FUN WITH MATH which designed to achieve with outmost skill and convenience. Back Next

16. The authors feel that you can benefit much from this modular workbook if you follow the direction carefully. Be mindful as you lead yourselves to challenge the situation and circumstances and as you faces in every living as well as for the near future. If you do these, you will realize that indeed this modular workbook can be a very interesting and helpful companion. The Authors Back Content

17. Acknowledgement Next Content

18. We would like to express our sincerest gratitude for the following whom in are ways or another help us making this modular workbook become possible: To Prof. Corazon N. San Agustin , for her kindness and understanding to this modular workbook. Next Back

19. To Mr. For – Ian V. Sandoval , our instructor and adviser in Educational Technology 2, for giving sufficient technical trainings, suggestions, constructive criticism and unending support in our every needs. To Assistant Professor Beatriz P. Raymundo , our Module Consultant, for making her available most of the time for comments, suggestions and revision of the modular workbook. Next Back

20. To Professor Lydia R. Chavez , our Dean, College of Education, for inspiring advises and encouragement. To our classmates and friends for their never ending support. Next Back

21. To our beloved families , for unconditional love, emotional, spiritual and financial support all the way to used and for the filling up our duties in our home. And most importantly to Almighty God , for rendering abilities, wisdom, good health, strength, courage, source of enlightenment and inspiration to pursue doing this piece of material. The Authors Content Back

22. Table of Contents

23. VMGO’s FOREWORD PREFACE ACKNOWLEDGEMENT TABLE OF CONTENTS

24. UNIT I Decimal Numbers Lesson 1 What is Decimal? Lesson 2 Reading and Writing Decimal Numbers Lesson 3 Reading and Writing Mixed Decimal Numbers Lesson 4 Reading and Writing Decimal Numbers Used in Technical and Science Work Lesson 5 Place Value Lesson 6 Comparing Decimal Numbers Lesson 7 Ordering Decimal Numbers Lesson 8 How to Round Decimal Numbers? Lesson 9 The Self-Replicating Gene

25. UNIT II Equivalent Fractions and Decimals Lesson 10 Expressing Fractions to Decimals Lesson 11 Expressing Mixed Fractional Numbers to Mixed Decimals Lesson 12 Expressing Decimals to Fractions Lesson 13 Expressing Mixed Decimals Numbers to Mixed Numbers (Fractions)

26. UNIT III Addition and Subtraction of Decimal Numbers Lesson 14 Meaning of Addition and Subtraction of Decimal Numbers Lesson 15 Addition and Subtraction of Decimal Numbers without Regrouping Lesson 16 Addition and Subtraction of Decimal Numbers with Regrouping Lesson 17 Adding and Subtracting Mixed Decimals Lesson 18 Estimating Sum and Difference of Whole Numbers and Decimals Lesson 19 Minuend with Two Zeros Lesson 20 Problem Solving Involving Addition and Subtraction of Decimal Numbers

27. UNIT IV Multiplication of Decimals Lesson 21 Meaning of Multiplication of Decimals Lesson 22 Multiplying Decimals Lesson 23 Multiplying Mixed Decimals by Whole Numbers Lesson 24 Multiplication of Mixed Decimals by Whole Numbers Lesson 25 Multiplying Decimals by 10, 100 and 1000 Lesson 26 Estimating Products of Decimal Numbers Lesson 27 Problem Solving Involving Multiplication of Decimal Numbers

28. UNIT V Division of Decimal Numbers Lesson 28 Meaning of Division of Decimals Lesson 29 Dividing Decimals by Whole Numbers Lesson 30 Dividing Mixed Decimals by Whole Numbers Lesson 31 Dividing Whole Numbers by Decimals Lesson 32 Dividing Whole Numbers by Mixed Decimals Lesson 33 Dividing Decimals by Decimals Lesson 34 Dividing Mixed Decimals by Mixed Decimals

29. CURRICULUM VITAE REFERENCES

30. UNIT I DECIMAL NUMBERS Content Next

31. OVERVIEW OF THE MODULAR WORKBOOK In this modular workbook, you will understand the concept of the language of decimal numbers. This modular workbook, will help you to read, write, and name decimal numbers for a given models, standard, mixed and technical and science work form. It provides the knowledge about place value, with the aid of a place - value chart. It also provides information on how to compare and order decimal numbers and also how to round off decimal numbers. This module will provide you a more difficult work in mathematics. Exercises will help the learners evaluate themselves to understand decimal numbers. Back Next

32. OBJECTIVES OF THE MODULAR WORKBOOK After completing this modular workbook, you expected to: 1. Know the language of decimal numbers. 2. Read, write, and name decimal numbers in different forms. 3. Read and write decimal numbers with the aids of place - value chart. 4. Compare and order decimal numbers. 5. Rounding off decimal numbers by following its rule. Back Next

34. One important feature of our number system is the decimal. It involved many computational operations. It is very useful in the measurement of very thin sheets and in the computation involving in exact amount. But what is decimal? Look at the following examples: Back Next

36. From the example given above, a “ decimal ” may be defined as a fraction whose denominator is in the power of 10. Back Next

37. Numbers in the power of 10 are 10, 100, 1000, 1000, etc. The dot before a digit in a decimal is called “ decimal point ” which is an indicator that the number is a decimal. The place on the position occupied by a digit at the right of the decimal point is called a “ decimal place ”. Back Exercises

38. I. Give the meaning and explain the use of the following. 1. What are decimals? 2. What is decimal point? 3. What is decimal place? 4. Give some examples of decimal numbers. Back Next 1 Worksheet

40. II. Change the decimal numbers to fractional form. Example: 0.8 = 8 10 1. 0.9 =_______________ 2. 0.1 =_______________ 3. 0.04 =_______________ 4. 0.06 =_______________ 5. 0.09 =_______________ 6. 0.001 =_______________ 7. 0.009 =_______________ 8. 0.0071 =_______________ 9. 0.0009 =_______________ 10. 0.0003 =_______________ Back Next

41. 11. 0.0004 =________________ 12. 0.0005 =________________ 13. 0.00008 =________________ 14. 0.00009 =________________ 15. 0.148 =________________ 16. 0.79 =________________ 17. 0.1459 =________________ 18. 0.6 =________________ 19. 0.01 =________________ 20. 0.051 =________________ Back Home

43. How to read and write decimals or decimal numbers? A decimal is read and write according to the number of decimal place it has. Here are the rules in reading and writing decimal numbers. Back Next

44. RULE I. A decimal of one decimal place is to be read and to be written as tenth. .4 is read as “4 tenths” and is to be written as “four tenths”; 4/10 .2 is read as “2 tenths” and is to be written as “two tenths”. 2/10 Back Next

45. RULE II. A decimal of two decimal places is to be read and to be written as hundredth. .35 is read as “35 hundredths” and is to be written as “thirty – five hundredths”; 35/100 .43 is read as “43 hundredths” and is to be written as “forty – three hundredths”.43/100 Back Next

46. RULE III. A decimal of three decimal places is to be read and written as thousandth. .261 is read as “261 thousandths” and is to be written as “two hundred sixty – one thousandths”; 261/1000 .578 is read as “578 thousandths” and is to be written as “five hundred seventy – eight thousandths”.578/1000 Back Next

47. RULE IV. A decimal of four decimal places is to be read and to be written as ten thousandth. .4917 is read as “4917 ten thousandths” and is to be written as “four thousand, nine hundred seventeen ten thousandths”; 4917/10,000 .5087 is read as “5087 ten thousandths” and is to be written as “five thousand eighty - seven ten thousandths”.5078/10,000 Back Next

48. A decimal is read and written like an integer with the name of the order of the right most digits added. Back Next tenths hundredths thousandths ten thousandths hundred thousandths Millionths ten millionths hundred millionths billionths ten billionths hundred billionths trillionths 0 . 4 3 5 7 8 9 6 1 2 5 3 4

49. Note: the names of the order of the different decimal places. Quadrillionths Pentillionths Hexillionths Heptillionths Octillionths Nonillionths Decillionths Undecillionths Dodecillionths Tridecillionths… SEQUENCES Back Next

51. 0.43578 Read as forty-three thousand, five hundred seventy-eight hundred thousandths. 0.435789 Read as four hundred thirty-five thousand, seven hundred eighty nine millionths. 0.4357896 Read as four million, three hundred fifty-seven thousand, eight hundred ninety-six ten millionths. Back Next

52. 0.43578961 Read as forty three million, five hundred seventy-eight thousand, nine hundred sixty-one hundred millionths. 0.435789612Read as four hundred thirty-five million, seven hundred eighty nine thousand, six hundred twelve billionths. 0.4357896125 Read as four billion, three hundred fifty seven million, eight hundred ninety six thousand, one hundred twenty five ten billionths. Back Next

53. 0.43578961253 Read as forty-three billion, five hundred seventy eight million, nine hundred sixty-one thousand, two hundred fifty three hundred billionths. 0.435789612534 Read as four hundred thirty-five billion, seven hundred eighty-nine million, six hundred twelve thousand, five hundred thirty-four trillionths. Back Exercises

54. I. Write each decimal numbers in words on the space provided. 1. 0.167213143____________________________ ______________________________________ 2. 0.52541876_____________________________ ______________________________________ 3. 0.263411859____________________________ ______________________________________ 4. 0.984562910____________________________ ______________________________________ 5. 0.439621512____________________________ _______________________________________ Back Next 2 Worksheet

55. II. Write the decimal number in standard form. 1. Nine tenths ______________________________________________ 2. Four hundredths ______________________________________________ 3. Two thousand, two hundred and two hundred thousandths ____________________________________________ 4. Four hundred seventy – six millionths ________________________________________________ 5. Forty thousand, one hundred forty – one millionths ________________________________________________ Back Home

57. Look at the following examples: a. 5.8 is read as “5 and 8 tenths” and is to be written as “five and eight tenths” b. 26.38 is read as “26 and 38 hundredths” and is to be written as “twenty – six and thirty – eight hundredths” c. 49.246 is read as “49 and 246 thousandths” and is to be written as “forty – nine and two hundred forty – six thousandths” d. 348.578 is read as “348 and 578 thousandths” and is to be written as “three hundred forty – eight and five hundred seventy – eight thousandths” Back Next

58. It is seen that the following rule has been followed in the above examples. RULE: In reading a mixed decimal numbers, read the integral part as usual “and” in place of the decimal point, the decimal point is read as usual also. Back Exercises

60. II. Write decimal numbers for each of the following sentences: 1. Sixteen and sixteen hundredths _____________________________________________ 2.Two and one ten – thousandths _____________________________________________ 3.Ten thousand four and fourteen ten – thousandths _____________________________________________ 4. Ninety – nine billion and eight tenths _____________________________________________ 5. Twelve hundred two and seven millionths _____________________________________________ Back Next

61. 6. Ninety – nine and nine hundred nine thousand, nine millionths_________________________________ 7. Five billion and sixty – five hundredths ______________________________________________ 8. Three billion, six thousand and three thousand six millionths _____________________________________ 9. Seventy – one million, one hundred and fifty – five hundred thousandths ______________________________________________ 10. Two hundred two million, two thousand, two and two hundred two thousand two millionths ______________________________________________ Content Home

63. This method of reading decimals and mixed decimals is often used by people engaged in technical and science work. But this can be used by lay people especially if the part of the number has many digits. Observe the following examples: Back Next

65. The rule followed in the above examples is as follows: To read decimals or mixed decimal numbers used in technical and science work or when the numbers of digits in the decimal is too many, just mention the values of the digits and separate the integral part by saying “point” instead of “and”. RULE: Back Exercises

67. 4. 3.456 Read:______________________________________ Write:______________________________________ 5. 47.629 Read: ___________________________________________ Write:___________________________________________ 6. 5.78456 Read: ___________________________________________ Write:___________________________________________ 7. 0.491 Read:___________________________________________ Write:__________________________________________ Back Next

68. 8. 28.652 Read:__________________________________________ Write:_________________________________________ 9. 4928.95 Read:__________________________________________ Write:_________________________________________ 9. 4928.95 Read:__________________________________________ Write:_________________________________________ 10. 376.732 Read:__________________________________________ Write:_________________________________________ Back Next

69. 11. 841.50 Read:__________________________________________ Write:_________________________________________ 12. 3.62 Read:__________________________________________ Write:_________________________________________ 13. 0.03 Read:__________________________________________ Write:_________________________________________ 14. 97.5 Read:__________________________________________ Write:________________________________________ 15. 2.3148 Read:_________________________________________ Write:________________________________________ Back Next

71. 6. three point seven six nine ______________________________________________ 7. two one seven point one five ____________________________________________ 8. point zero eight zero zero zero ___________________________________________ 9. nine point zero four zero ______________________________________________ 10. two point six seven two five ____________________________________________ 11. zero point nine eight nine ______________________________________________ Back Next

72. 12. zero point five two six eight two nine ____________________________________________ 13. five six zero point four zero one eight ____________________________________________ 14. one point one nine one eight ____________________________________________ 15. eight point five four three ____________________________________________ Back Home

74. Back Next PLACE VALUE CHART Place Value Names M I L L I O N S H T U H N O D U R S E A D N D S T T E H N O U S A N D S T H O U S A N D S H U N D R E D S T E N S O N E S T E N T H S H U N D R E D T H S T H O U S A N T H S T T E H N O U S A N T H S H T U H N O D U R S E A D N T H S M I L L I O N T H S Numerals 1 9 4 6 3 4 1 . 1 3 4 5 8 7 × × × × × × × . × × × × × × 10 6 10 5 10 4 10 3 10 2 10 1 1/10 0 1/10 1 1/10 2 1/10 3 1/10 4 1/10 5 1/10 6

75. What relationship exists in the diagram? What does the 1 in the tenths place mean? What does the 3 in the hundreds place represent? How about the 3 in the hundredths place? Back Next

76. Notice that: 0.1 = 1 × 1/10 = 1/10 (one tenth) 0.13 = 13 × 1/102 = 13/100 (thirteen hundredths) 0.134 = 134 × 1/103 = 134/1000 (one hundred thirty – four thousandths) 0.1345 = 1345 × 1/104 = 1345/10000 (one thousand three hundred forty – five ten thousandths) 0.13458 = 13458 × 1/105 = 13458/100000 (thirteen thousand four hundred fifty – eight hundred thousandths) 0.134587 = 134587 × 1/106 = 134587/1000000 (one hundred thirty – four thousand five hundred eighty – seven millionths) Back Exercises

77. Worksheet I. Complete the equivalent decimals to fractions. Back Next 5 Decimal Fraction 1. 0.23 2. 4.165 3. 0.937 4. 1.52 5. 0.041 6. 2.003 7. 0.1527 8. 16.775 9. 0.000658 10. 685.95

78. II. Answer the following. 1. In 246.819, what number is in each of the following place value? Example: __ 6 __ a. ones _ 246 _ c. hundreds _ 46 __ b. tens _ _.8 __ d. tenths _ .81 __ e. hundredths __ .819 _ f. thousandths 2. In 65.42387, tell what number is in each of the following places. _____a. tenths _____d. ten–thousandths _____b. hundredths _____e. hundred – thousandths _____c. thousandths _____f. ones _____g. tens Back Next

79. 3. In 9023.45867, tell what number is in each of the following places. _____a. ones _____e. hundredths _____b. tens _____f. thousandths _____c. tenths _____g. thousands _____d. hundreds _____h. ten – thousandths _____i. hundred–thousandths _____j. millionths Back Home

81. If there are two decimal numbers we can compare them. One number is either greater than (>), less than (<) or equal to (=) the other number. Back Next

82. A decimal number is just a fractional number. Comparing 0.7 and 0.07 is clearer if we compared 7/10 to 7/100. The fraction 7/10 is equivalent to 70/100 which is clearly larger than 7/1000. Back Next

83. Therefore, when decimals are compared start with tenths place and then hundredths place, etc. If one decimal has a higher number in the tenths place then it is larger than a decimal with fewer tenths. If the tenths are equal, compare the hundredths, then the thousandths, etc. Until one decimal is larger or there are no more places to compare. If each decimal place value is the same then the decimals are equal. Back Exercises

84. Worksheet I. Fill the frame with the correct sign (>) “less than”, (=) “equal to”, or (>) “greater than” between two given numbers. Example: 0.9 = 9/10 0.90 = 10/100 = Back Next 6

85. b. 9.004 0.040 f. 51.6 51.59 c. 20.80533 20.06 g. 50.470 50.469 d. 0.070 0.07 h. 0.90 0.9 e. 0.540 0.054 i. 0.003 0.03 j. 0.8000 0.080 Back Home

87. Numbers have an order or arrangement. The number two is between one and three. Three or more numbers can be placed in order. A number may come before the other numbers or it may come between them or after them. Back Next

89. REMEMBER: The order may be ascending (getting larger in value) or descending (becoming smaller in value). Back Exercises

90. I. Write in order from ascending order and descending order by completing the table. Back Next 7 Worksheet Ascending Order Descending Order 1. 2.0342; 2.3042; 2.3104 Example: 2.0342 2.3042 2.3104 2.3104 2.3042 2.0342 2. 5; 5.012; 5.1; .502 3. 0.6; 0.6065; 0.6059;0.6061

91. Back Next 5. 6.3942; 6.3924; 6.9342; 6.4269 6. 0.0990; 0.0099; 0.999; 0.90 7. 3.01; 3.001; 3.1; 3.001 8. 0.123; 0.112; 0.12; 0.121 9. 7.635; 7.628; 7.63; 7.625 4. 12.9; 12.09; 12.9100; 12.9150; 12 10. 4.349; 4.34; 4. 3600; 4.3560

92. FUN WITH MATH!!! Arrange the given decimal numbers from the least to greatest and you will find a famous quotation by Shakespeare. Back Next

93. Back Next Shakespeare (least) 7.301 All 8.043 climb 7.8 except 7.310 ambitious 8.88 or 7.84 those 9.100 of 7.911 which 10.5 mankind 7.33 are 8.43 up 8.513 upward 7.352 lawful 8.901 the 9.003 miseries

94. All ___ _______ ________ ________ ________ ________ 7.301 _______ ________ ________ ________ ________ _______ ________ ________ ________ ________ ________ _______ ________ ________ ________ ________ ________ _______ ________ ________ _______ ________ ________ . - Shakespeare II. Answer the following. a. The list below is the memory recall time of 5 personal computers. Which model has the fastest memory recall? Back Next

95. Answer: ___________________________________________ ___________________________________________ Back Next Model Recall Time Sterling PC 0.0195 sec. XQR 2000 0.01936 sec. Redi-mate 0.02045 sec. Vision 0.1897 sec. Sal 970 0.019 sec.

96. b. Arrange the memory recall time of computers in number 1 in ascending order. Answer: __________________________________________________________________________________ c. A carpenter uses different sizes of drill bits in boring holes. The sizes are in fractional form and their equivalent decimals. Arrange the decimal equivalent in descending order. 1/16 = 0.0625 ¼ = 0.25 1/8 = 0.125 5/6 = 0.3125 Back Next

97. Answer: ___________________________________________ ___________________________________________ d. Which has the smallest decimal equivalent among the drill bits in item C? Answer: ________________________________________ ________________________________________ Back Next

98. e. Which has the greatest decimal equivalent the drill bits in item C? Answer: ________________________________________ ________________________________________ Back Home

100. To round decimal numbers means to drop off the digits to the right of the place-value indicated and replace them by zeros. The accuracy of the place-value needed must be stated and it depends on the purpose for which rounding is done. We give rounded decimal numbers when we do not need the exact value or number. Instead, we are after an estimated value or measure that will serve our purpose. These are many instances in daily life when rounded numbers are what we need to use. Back Next

101. How well do you remember in rounding whole numbers? Study the example below. Round to the nearest 4935 ten 4940 hundred 4900 thousand 5000 Back Next

104. Example: Round off 78.4651 to the nearest hundredths. 7 8 . 4 6 5 1 = 78.47 Dropping digit Decimal number to be rounded off Examples: Round the following. a. 5.767 to the nearest tenths = 5.8 Since the digit to the right of 7 is 6. Back Next

105. b. 65.499 to the nearest hundredths = 65.50 Since the digit to the right of 9 is 9. c. 896.4321 to the nearest thousandths = 896.432 Since the digit to the right of 2 is 1. d. 32.28 to the nearest tenths = 32.3 Since the digit to the right of 2 is 8 e. 1000.756 to the nearest hundredths = 1000.80 Since the digit to the right of 5 is 6 f. 56.58691 to the nearest thousandths = 56.5870 Since the digit to the right of 6 is 9 Back Exercises

107. 2. 3.097591 to the nearest: a. ones _______________________ b. tenths _______________________ c. hundredths _______________________ d. thousandths _______________________ e. ten-thousandths _______________________ 3. 6.152292 to the nearest: a. ones ______________________ b. tenths ______________________ c. hundredths ______________________ d. thousandths ______________________ e. ten-thousandths ______________________ Back Next

108. 4. 10.01856 to the nearest: a. ones ____________________ b. tenths ____________________ c. hundredths ____________________ d. thousandths ____________________ e. ten-thousandths ____________________ 5. 123.831408 to the nearest: a. ones ____________________ b. tenths ____________________ c. hundredths ____________________ d. thousandths ____________________ e. ten-thousandths ____________________ Back Next

111. IV. Answer the following with TRUE or FALSE. ________________ 1. 0.32 rounded to the nearest tenths is 0.3. ________________ 2. 0.084 rounded to the nearest hundredths is 0.09. ________________3. 0.483 rounded to the nearest thousandths is 0.048. ________________4. 0.075 rounded to the nearest hundredths is 0.06. ________________5. 0.375 rounded to the nearest tenths is 0.4. Back Next

112. V. Round each of the following by completing the tables. Number 1 serves as an example. Back Next Decimals Round to the nearest Tenths Hundredths Thousandths Ten Thousandths Example: 1. 0.89432 0.9 0.89 0.894 0.8943 2. 5.09998 3. 2.96425 4. 5.2358 5. 5.39485 6. 0.86302 7. 28154 8. 42356

113. Back Next 9. 2.38425 10. 0.56893 11. 2.9625 12. 62.84213 13. 29.04347 14. 85.42998 15. 1539485

114. FUN WITH MATH!!! I. Find the answer by rounding off to the nearest place value indicated. Draw a line to the correct rounded number. Each line will pass through a letter. Write the letter next to the rounded number. ONES 1.6 ● ● 1.63 __________ 5.38 ● ● 3.4 __________ 52.52 ● ● 2 __________ TENTHS 0.45 ● ● 3.433 __________ 3.421 ● ● 53 __________ 12.76 ● ● 0.35 __________ 88.55 ● ● 5 __________ HUNDREDTHS 0.345 ● ● 12.8 __________ 1.634 ● ● 0.044 __________ 13.479 ● ● 0.5 __________ 201.045 ● ● 11.68 __________ 11.677 ● ● 16.778 __________ THOUSANDTHS 0.0437 ● ● 88.6 __________ 3.4325 ● ● 105.312 __________ 16.7777 ● ● 13.48 __________ 23.40092 ● ● 23.401 __________ 105.31238 ● ● 201.05 __________ T V E H W G E N T O O L H M S E T What happened to the man who stole the calendar? Back Home

115. Lesson 9 FACTS AND FIGURES (The self-replicating Gene) or centuries, generations of scientists in Numerica had been working relentlessly on what had been dubbed as The Genetic Enterprise. It was founded for the purpose of controlling a runaway gene that had beleaguered the Decimal citizens of Numerica for millennia: the repeating decimal gene. F Content Next 4 ___ 44

116. Their history revealed that it all began when a woman named Four (4) united with a man named Forty-Four (44) positioned as 4/44. Their first offspring, a fraction, came out all right, and they named her Three-Thirty-thirds (3/33). Such a beautiful fraction she was. But their second child came out with the first problematic replicating gene--- the boy looked different and came with a long tail: 0.0909090909… Arbitrarily multiplying both sides of the equation by any power of ten does not change the value of the decimal nor does it destroy the balance of the equation. This is because of the Multiplication Property of Equality of the Real Numbers. Back Next

117. That wasn’t the end of it. Every week, the boy’s tail added a new segment of 09, and it just never ended! It wasn’t so much the unusual appearance of the boy that worried every one, as the difficulty of naming him. Point-Zero-Nine-Zero-Nine-Zero-Nine- Zero -Nine-Zero-Nine, going on forever, was just too long a name! There were many others in the community whose tails also continuously and regularly increased. Despite their peculiar form, though, those trouble with the repeating gene were never shunned, were treated equally with love, respect, and total acceptance. Still, the continually growing tail proved cumbersome for the Decimals, and they prayed to be changed to regular forms. Back Next

118. Arbitrarily multiplying both sides of the equation by any power of ten does not change the value of the decimal nor does it destroy the balance of the equation. This is because of the Multiplication Property of Equality of the Real Numbers. Back Next Remember

119. One fateful day, the newspaper headlines screamed: “The Genetic Enterprise: Finally Success!” All of Numerica was thrilled! At the state conference the next day, every citizen was present, especially those with continuously growing tails. “ And now, I must ask for a volunteer,” said Doctor One Half (½), head scientist of the project, over the microphone. Immediately, 0.33333…, friend of Point-Zero-Nine-Zero-Nine…, was up the stage. “ O-Point-Three-Three-Three…” One Half began, “do not be afraid. Go into that glass capsule to your left, for we must first clone you.” Back Next

120. The crowd was aghast. One Half reassured every one immediately. “Do not worry, it is only temporary.” When 0.33333… came out, his clone came out from the other capsule. The doctor spoke again. “I will run you all through the process as we proceed. First, we shall designate the clone as Ex = 0.33333… “ Now, 0.33333…, go back into the capsule---we will introduce a new gene into you. This gene is called Tenn (10), and this will change your appearance, so that we will temporarily call you Tennexx (10x). Do not be alarmed!” One Half added quickly at every one’s reaction. Back Next

121. When 0.33333… stepped out of the capsule, he had become 3.33333… 10x = 10 x 0.3333… = 3.3333… 10x = 3.3333… The crowd was mesmerized. “ Tennexx, go back into the capsule. Exx, go into the other capsule. This time, we shall remove the repeating gene from Tennexx---by taking out Exx!” 10x – x = 3.3333… - 0.333… 9x = 3 Now, Tennex come out! Let us all see what you have become…” One Half said dramatically. Back Next

122. The purpose of assigning a variable and multiplying both sides of the equation by 10 is to come up with whole numbers on both sides of the equation (on one side, with the variable, and on the other side of the equation, with just an integer). From this form we obtain a fraction equal to the original decimal. Note when finally making a subtraction, the digits in the decimal parts MUST be the same in order for the difference to be an integer. FACT BYTES Back Next

123. When Tennex came out, he had become 1/3. 9x = 3 x = 3/9 or 1/3 The applause was thunderous! 1/3 spoke on the microphone, tears of joy poring down his cheeks. “Once! Was Zero-point-Three- -Three-Three-Three-Three… now I am One-Third. Thank you, Doctor One Half!” he said. Back Next

124. LESSON LEARNED In the article, we see that there is still hope for repeating Decimal genes like Point O Nine O Nine O Nine and O Point Three-Three-Three. It is all about representing them using any variable, say, x, and taking away their never-ending tail. Any repeating decimal represents a geometric series 0.3333… is 0.3 + 0.03+ 0.03 +… The common ratio is 0.1, that is, the next term is obtained by multiplying the previous term by 0.1. The formula S= a1/1-r may be used if (r) < 1. S = a1/1-r S = 0.3/1-0.1 = 0.3/0.9 or 1/3 FACT BYTES Back Next 1 __ 3

125. PROBLEM BUSTER A DIFFERENT GENE May I have another Volunteer? Ah, yes. 0.83333 Do you think we can change 0.833333...in exactly the same way as what we did to 0.33333…? Notice that in this case, the numeral 8 does not repeat. If we introduced 10 like we did to0.33333…, by multip- lying 0.833333…by 10, 0.833333…will become 8.33333… Following the process, we have, 10x –x = 8.33333… - 0.833333… which is the same as 9x =7.5 where the right side of the equation is not an integer! What are we to do? Back Next 1 / 2 1 / 2

128. II. Change the following to fraction in simplest form. 3. 0.77777… 4. 0.9166666… 5. 0.9545454… 6. 0.891891891… 7. 0.153846153846153846… 8. 0.9692307692307692307… Back Home

129. Unit II EQUIVALENT FRACTIONS AND DECIMALS Content Next

131. After completing this Unit, you are expected to: 1. Transform fraction/mixed fractional numbers to decimals/mixed decimal. 2. Change decimal/mixed decimal to fraction /mixed numbers (fractions). 3. Follow the rules in expressing equivalent fractions and decimals. OBJECTIVES OF THE MODULAR WORKBOOK Back Next

133. Decimals are a type of fractional number. Let us now study how to write fractions to decimal form. Back Next

134. We will apply the principle of equality of fractions that is, if a/b =c/d then ad = bc . Back Next

135. Example 1: Write the fraction 2/5 as a tenth decimal. In this case we are interested to find the value of x such that 2/5=x/10. Since the two fractions name the same rational number, we can proceed: 5x = 2(10) – applying equality principle 5x = 20 x = 20/5 or 4 Hence, 2/5 = 4/10 = 0.4 Back Next

136. Example 2: Write the fraction 3 as a hundredth decimal. We are 4 interested to find the value of x such 3 that = x . 4 100 Applying the principle of equality we have 4x = 3(100) 4x = 300 x = 75 Hence, ¾ = 75/100 = 0.75 Back Next

137. On the other hand, fractions can also be expressed as a decimal without using the equality principle. Instead we have to think of a fraction as a quotient of two integers that is a/b=a = a b. Example 3: Express 2/5 as a decimal. Expressing 2/5 as quotient of 2 and 5 we have 2/5 = 0.4 Back Next

138. RULE To change a fraction to decimal, divide the numerator by the denominator up to the desired number of decimal places. Back Exercises

139. I. Give the meaning and explain the use of the following 1. How to change fractions to decimal? 2. What are the rules in changing fractions to decimals? 3. What is decimal? 4. Give some examples of fractions to decimals. Back Next 10 Worksheet

143. FUN WITH MATH!!! It was very fortunate that Sophie Germain , a woman mathematician was born at a time when people looked down on women. In 1776, women then were not allowed to study formal, higher level mathematics. Thus, this persistent woman reads books of famous mathematicians and studied on her own. Aware of her situation, she shared her theorems and mathematical formulae to other mathematicians and teachers through correspondence using a pseudonym. Back Next

144. Can you guess the pseudonym that she used? Yes, you can. Simply follow the instruction. Back Next

145. Select the right answer to the equation below. Write the letter of the correct answer on the respective number decode pseudonym that she used. You may use the letter twice. ______ ______ ______ ______ (1) (2) (3) (4) ______ ______ ______ ______ (5) (6) (7) (8) ______ ______ ______ (9) (10) (11) ______ ______ ______ ______ (12) (13) (14) (15) Back Next

146. Answers: A = 0.25 F = 0.65 K = 0.512 P = 0.27 B = 0.15 G = 0.28 L = 0.125 Q = 0.006 C = 0.6 H = 0.77 M = 0.333… R = 0.72 D = 0.54 I = 0.24 N = 0.40 S = 0.6 E = 0.76 J = 0.532 O = 0.75 T = 0.4113 U = 0.325 Back Home

148. How can we change mixed fractional numbers to mixed decimals? See the following examples. 4 1/2 = 4.5 c. 21 1/8 = 21.125 14 3/8 = 14.375 d. 32 3/7 = 32.4285 Back Next

149. From the examples given above, it can be seen that the rule in changing a mixed fractional number to mixed decimal is: Back Next

150. RULE To change a mixed fractional number to a mixed decimal, change the fraction to decimal up to the number of decimal places desired and then annex it to the integral part. Back Exercises

152. 8. 2 ¼ = _______________ 9. 3 5/7 = _______________ 10. 4 ½ = _______________ 11. 8 ¼ = _______________ 12. 2 1/3 = _______________ 13. 5 4/6 = _______________ 14. 10 4/5 = _______________ 15. 3 ¼ = _______________ 16. 10 3/7 = _______________ 17.10 11/20 = _______________ 18. 8 3/10 = _______________ 19. 6 15/16 = _______________ 20. 8 1/10 =_______________ Back Next

154. 5. 9 6/100 a. 9.16 b. 9.600 c. 9.006 d. 9.06 Back Home

156. As what we have learned earlier, decimals are common fractions written in different way. Back Next

157. There are certain instances when it becomes necessary to change decimal into fraction. Hence, it is necessary to acquire skill in changing a decimal to faction. Now we will study how to write decimals in fractions. Back Next

158. Example 1: Write 0.5 in a faction form. 5 or 1 10 2 0.5 = 5(1/10) Example 2: Write 0.72 in a fraction form. 0.72 = 7(1/10) + 2(1/100) 18 25 = 72/100 or 18 25 Back Next

159. On the other hand, a simple way of expressing decimal to factions is possible without writing the numeral in expanded form. What we need is only to determine the place value of the last digit as we read if from left to right. Back Next

160. Example 1: Write 0.5 in a faction form. Notice that the digit 5 is in the tenth place, we can write immediately: 0.5 = or 1 2 __ 5 __ 1000 Back Next

161. The digit 2 is in the thousandths place so we write: 0.072 = 72/1000 = 9/125 Back Next

163. Identifying Equivalent Decimals and Fractions Decimals are a type of fractional number. The decimal 0.5 represents the fraction 5/10. The decimal 0.25 represents the fraction 25/100. Decimal fractions always have a denominator based on a power of 10. We know that 5/10 is equivalent to 1/2 since 1/2 times 5/5 is 5/10. Therefore, the decimal 0.5 is equivalent to 1/2 or 2/4, etc. Back Next

164. It can be seen from the examples above the rule in changing a decimal to fraction is as follows: Back Next

165. RULE To change a decimal number to a fraction, discard the decimal point and the zeros at the left of the left-most non-zero digit and write the remaining digits over the indicated denominator and reduce the resulting fraction to its lowest terms. (The number of zeros in the denominator is equal to the number of decimal places in the decimal number. Back Exercises

166. Worksheet Change the following decimals to factional form and simplify them. 1. 0.4 = ________________ 2. 0.007 = ________________ 3. 0.603 = ________________ 4. 0896 = ________________ 5. 056 = ________________ 6. 0.06 = ________________ 7. 0.125 = ________________ 8. 0.5 = ________________ 9. 0.42857 = ________________ 10. 0.375 = ________________ Back Next 12

167. 11. 0.54 = ________________ 12. 0.14 = ________________ 13. 0.8187 = ________________ 14. 0.956 = ________________ 15. 0.3567 = ________________ 16. 0.578 =_________________ 17. 0.34878 =_________________ 18. 0.47891 =_________________ 19. 0.12489 =_________________ 10. 0.14789 =_________________ Back Next

168. FUN WITH MATH!!! How can you make a tall man short? To find the answer, change the following decimal number to lowest factional form. Each time an answer is given in the code, write the letter for that exercise. Back Next

169. 1. 0.6 = A 6. 0.24 = _______ O 2. 0.5 = __ _____ B 7. 0.125 = _______ H 3. 0.7 = _______ N 8. 0.55 = _______ L 4. 0.4 = _______ I 9. 0.3 = _______ W 5. 0.75 = _______ O 10. 0.048 = _______ R 11. 0.25 = ______ O 12. 0.75 = _____ L 13. 0.2 = _____ E 14. 0.225 =______ O 15. 0.24 = _____ Y 16. 0.8 = _____ S 17. 0.5688=______ R Back Next

170. _____ _____ _____ ______ ______ _____ ½ 6/25 6/125 711/1250 225/ 1000 3/10 __ A ___ ______ ______ 3/5 ¾ 11/20 _____ ______ ______ 1/8 4/10 12/15 _____ _____ _____ _____ _______ 8/32 12/16 14/20 18/90 36/150 Back Home

172. How can we change mixed decimals to mixed fractions? Study the following examples: Back Next

174. Worksheet Change the following mixed decimals to mixed fractional numbers. (First is an example.) 1. 3.06 = 3 6/10 6. 67.7362 = ___________ 2. 5.72 = ________ 7. 62.72 = ___________ 3. 11.302 = ________ 8. 71.4684 = ___________ 4. 10.642 = ________ 9. 92.5896 = __________ 5. 51.136 = ________ 10. 4.789 = __________ Back Next 13

175. II. Identify the following by writing D if it is mixed decimals and F if it is mixed fractional numbers. _____1. 1 217/100 _____ 11. 14.3245 _____ 2. 1.0124 _____ 12. 18 18/24 _____ 3. 1.4568 _____ 13. 9.28 _____ 4. 32 8/18 _____ 14. 1.0406 _____ 5. 2.510 _____ 15. 4 235/1000 _____ 6. 10.01 _____ 16. 450 11 /111 _____ 7. 39 45/100 _____ 17. 1.5345 _____ 8. 45 105/265 _____ 18. 143.445254 _____ 9. 101 81/411 _____ 19. 12 34/91 _____ 10. 1.01123 _____ 20. 653 185/1124 Back Home

176. Unit III ADDITION AND SUBTRACTION OF DECIMALS NUMBERS Content Next

177. OVERVIEW OF THE MODULAR WORKBOOK This modular workbook provides you greater understanding in all aspects of addition and subtraction of decimal numbers. It enables you to perform the operation correctly and critically. It includes all the needed information about the addition and subtraction of decimal numbers, its terminologists to remember, how to add and how to subtract decimals with or without regrouping, how to estimate sum and differences, and subtracting decimal numbers involving zeros in minuends. This modular work will help you to enhance your minds and ability in answering problems deeper understanding and analysis regarding all aspects of adding and subtracting decimal numbers. Back Next

178. OBJECTIVES OF THE MODULAR WORKBOOK After completing this Unit, you are expected to: 1. Familiarize the language in addition and subtraction. 2. Learn how to add and subtract decimal numbers with or without regrouping. 3. Know how to check the answers. 4. Estimate the sum and differences and how it is done. 5. Know how to subtract decimal numbers with zeros in the minuend. 6. Develop speed in adding and subtracting decimal numbers. 7. Analyze problems critically. Back Next

180. Addition is the process of combining together two or more decimal numbers. It is putting together two groups or sets of thing or people. Back Next

181. Example: 0.5 + 0.3 = 0.8 Addends Sum or Total Addends are the decimal numbers that are added. Sum is the answer in addition. The symbol used for addition is the plus sign (+). Back Next

182. The process of taking one number or quantity from another is called Subtraction . It is undoing process or inverse operation of addition. It is an operation of taking away a part of a set or group of things or people. Note: Decimal points is arrange in one column like in addition of decimals. Back Next

184. Worksheet I. Give the meaning and explain the use of the following. 1. What is addition? 2. What is subtraction? 3. What are the parts of addition? 4. What are the parts of subtraction? Back Next 14

185. 1. Addition ______________________________________________ 2 Subtraction ______________________________________________ 3. Parts of addition ______________________________________________ 4. Parts of subtraction ______________________________________________ Back Next

186. II. Identify the following decimal numbers whether it is addends, sum, minuend, subtrahend or difference. Put an if addends, if sum, if minuend, if subtrahend and if difference. 1. 0.9 _______ + 0.8 _______ 1.7 _______ 2. 2.24 _______ + 2.38 _______ 4.62 _______ 3. 12.85 _______ - 0. 87 _______ 11.98 _______ 4. 7.602 _______ - 2.664 _______ 4.938 _______ Back Next

187. 5. 0.312 _______ + 0.050 _______ 0.362 _______ 6. 6.781 _______ - 1.89 _______ 8.676 _______ 7. 0.215 _______ + 0.001 _______ 0.216 _______ 8. 0.156 _______ + 1.811 _______ 1.967 _______ 9. 0.113 _______ + 0.009 _______ 0.122 _______ 10. 0.689 _______ - 1.510 _______ 2.199 _______ Back Next

188. III. Answer the following by completing the letter in each box which indicate the parts of addition and subtraction of decimals. 1. It is the numbers that are added. 2. The answer in addition. 3. It is the process of combining together two or more numbers. Back Next

189. 4. Sign used for addition. 5. It is undoing process or inverse operation of addition. 6. Sign used for subtraction. 7. It is the answer in subtraction. Back Next

190. 8. It is in the top place and the bigger number in subtraction. 9. It is the smaller number in subtraction. 10. Subtraction is an operation of _________ a part of a set or group of things or people. Back Home

192. Add the following decimals: 28. 143 and 11.721. If you added them this way, you are right. 28. 143 + 11. 721 39. 864 Let us add the decimals by following these steps. Back Next

193. STEP 1 STEP 2 Back Next Add the thousandths place 3+ 1 = 4 28. 143 + 11. 721 4 Add the hundredths place 4 + 2 = 6 28. 143 + 11. 721 64

194. STEP 3 STEP 4 Back Next Add the tenths place 7 + 1 = 8 28. 143 + 11. 721 864 Add the following up to the ones. 8 + 1 = 9 28. 143 + 11. 721 9. 864

195. STEP 5 Back Next Add the following up to the tens. 2 + 1 = 3 28. 143 + 11. 721 39. 864

196. Now subtract 39. 864 to 11. 721. 39. 864 minuend - 11. 721 subtrahend 28. 143 difference Back Next

197. 2 Ways of Checking the Answer 1. minuend – difference = subtrahend 39. 864 minuend - 28. 143 difference 11. 721 subtrahend 2. difference + subtrahend = minuend 28. 143 difference + 11. 721 subtrahend 39. 864 minuend Back Next

198. If you subtract the difference from minuend and the answer is subtrahend the answer is correct. Also, adding the difference and subtrahend will the result to the minuend: it is also correct. Back Next

200. Worksheet Add and subtract as fast as you can. Back Next 15

201. Back Next

202. FUN WITH MATH!!! Add and subtract the following to find the mystery words and write the letter of each answer in the code below. This appears twice in the Bible (In Matthew VI and Luke II). Back Next

206. In the past lesson, you’ve learned how to add and subtract decimal numbers without regrouping. The only difference in this lesson is that it involves regrouping and borrowing. It is easy to add and subtract decimal numbers without regrouping. Back Next

207. Regrouping is a process of putting numbers in their proper place values in our number system to make it easier to add and subtract. Here’s how to add decimal numbers with regrouping. Back Next

208. Example 1: 0. 7 + 0. 5 0.7 + 0.5 = 12 10 tenths is regroup as ( 1 ) one. Back Next Ones . Tenths 1 0 + 0 . . 7 5 1 . 2

209. Example 2: 0.09 + 0.06 0.9 + 0.6 = 15 hundredths 10 hundredths is 1 regrouped as 1 tenth. Back Next O . T H 0 0 . . 0 0 9 6 0 . 1 5

210. Example 3: 0.065 + 0.008 5 + 8 = 13 thousandths 10 thousandths is regrouped as 1 hundredth. Back Next O T H Th 0. + 0. 0 0 6 0 5 8 0. 0 7 3

211. Subtract decimals like you were subtracting whole numbers. Back Next

213. Example 5: 0.730 - 0.518 2 10 0.730 - 0.518 0.212 Check: 0.518 + 0.212 0.730 Answer Back Exercises ones tenths hundredths thousandths 0. 7 3 0 0. 7 2+1 10 0. 7 - 5 2 - 1 0 - 8 0. 0. 2 1 2

215. B. Subtract the following and check your answer on the Check Box below. 1. 0.62 2. 0.762 - 0.58 - 0.325 3. 0.850 4. 0.452 - 0.328 - 0.235 Back Next

218. Ramon traveled from his house to school, a distance of 1.39845 kilometers. After class, he traveled to his friend’s house 1.85672 kilometer away in another direction. From his friends to his own house, he rode another 1.23714 km over. How many kilometers did Ramon traveled? Back Next 3 . T H Th T Th H Th 1 1 1 +1 . . . 1 3 8 2 2 9 5 3 1 8 6 7 1 4 7 1 5 2 4 4 . 4 9 2 3 1

219. He traveled a total of 4.49231 km. The following day, he traveled to the school and the seashore for a total of 6.35021 km. How many more kilometers did Ramon traveled than previous day? Back Next O T H Th T Th H Th 5 6 -4 . . 12 3 4 14 5 9 9 0 2 12 2 3 1 1 1 . 8 5 7 9 0

220. Ramon traveled 1.85790 kilometers more. In adding and subtracting mixed decimals, remember to align the decimal points and regroup when necessary. Back Exercises

223. 4. 18.16532 9. 5.306321 - 4.01985 002.7509 + 4.952005 5. 951.235 7.18902 10. 103.93284 + 00.3 + 43.76895 Back Home

225. Estimation is a way of answering a problem which does not require an exact answer. An estimate is all that is needed when an exact value is not possible. Estimation is easy to use and or to compute. Rounding is one way of making estimation. Each decimal number is rounding to some place value, usually to the greatest value and the necessary operation is performance on the rounded decimal numbers. Back Next

226. Two methods are used in making estimation, the rounding off the desired digit one and finding the sum of the first digit only. We have learned how to round decimal numbers in this section, first only the front digits are used. If an improved or refined estimate is desired, the next digits are used. Back Next

229. Thus the sum 3.455 + 2.672 + 5.134 can be roughly estimated by 11.000. If a better estimate is required or desired, then add 1.300 to get 11.300. Back Next

230. Estimate 5.472147 – 2.976543 Rounded to the nearest ones Actual Subtraction 5.472147 5.000000 5.472147 - 2.976543 - 3.000000 - 2.976543 2.000000 2.495604 Back Next

232. b. Estimate the difference by rounding method. Example : 14.525 15.000 - 11.018 - 11.000 4.000 By the rounding method, the first example is estimated by 17.000 and the second one by 4.000. The actual value of the sum of example no.1 is 16.668 and the difference of example no. 2 is 3.507 respectively. Both methods give a reasonable estimate. Back Next

233. Remember: In estimating the sums, first round each addend to its greatest place value position. Then add. If the estimate is close to the exact sum, it is a good estimate. Estimating helps you expect the exact answer to be about a little less or a little more than the estimate. However, in estimating difference, first round the decimal number to the nearest place value asked for. Then subtract the rounded decimal numbers. Check the result by actual subtraction. Back Exercises

234. Worksheet I. Estimates the sum and difference to the greatest place value. Check how close the estimated sum (E.S.) / estimated difference (E.D.) by getting the actual sum (A.S.) and actual difference (A.D.) . A. Actual Sum/ Estimated Sum 1. 3.417 3.000 2. 36.243 36.000 2.719 3.000 29.641 30.000 + 1.829 + 2.00 + 110.278 + 110.000 A.S. E.S. A.S. E.S. Back Next 18

235. 3. 648.937 649.000 4. 871.055 871.000 214.562 215.000 276.386 276.000 + 450.211 + 450.000 + 107.891 + 108.000 A.S. E.S. A.S. E.S. 5. 374.738 375.000 6. 342.165 342.000 469.345 469.000 178.627 179.000 + 213.543 + 213.500 + 748.715 + 749.000 A.S. E.S. A.S. E.S. Back Next

236. B. Actual Difference/ Estimated Difference 7. 14.255 14.000 8. 28.267 28.000 - 11.812 - 12.000 - 16.380 - 16.000 A.D. E.D A.D. E.D. 9. 345.678 346.000 10. 92.365 92.000 - 212.792 - 213.000 - 75.647 - 76.000 A.D. E.D. A.D. E.D. 11. 62.495 62.000 12. 9.2875 9.0000 - 17.928 - 18.000 - 6.8340 - 7.0000 A.D. E.D. A.D. E.D. Back Next

237. FUN WITH MATH!!! Match a given decimals with the correct estimated sum / difference to the greatest place – value. The shortest verse in the Bible consists of two words. Back Next

238. To find out, connect each decimals with he correct estimated sum / difference to the greatest place – value. Write the letter that corresponds to the correct answer below it. 1. 36.5+18.91+55.41 U. 939.00 2. 639.27-422.30 S. 216.00 3. 48.21+168.2 P. 2.0000 4. 285.15+27.35+627.30 E. 146.000 5. 8.941-8.149 W. 28.10 6. 18.95+9.25 J. 111.00 7. 129.235+16.41 T. 537.00 8. 9.2875-6.834 S. 1.000 9. 989.15-451.85 E. 217.00 Back Next

239. _____ ______ ______ ______ ______ 1 2 3 4 5 _____ ______ ______ ______ 6 7 8 9 Back Home

241. You always have to regroup in subtracting decimal numbers with zeros. You will have to regroup from one place to the next until all successive zeros are renamed and ready for subtraction. Back Next

243. Example: 0.8005 - 0.6372 Back Next O T H Th T Th 0. 8 0 0 5 0. 7+1 10 9+1 10 0. 7 9 10 5 0. 6 3 7 2 0. 1 6 3 3

244. Rewriting: 0.8005 - 0.6372 Difference 0.1633 Checking: 0.6372 + 0.1633 0.8005 Back Exercises

246. FUN WITH MATH!!! Answer the following to find the mystery words. In what type of ball can you carry? To find the answer, draw a line connecting each decimal number with its equal difference. The lines pass through a box with a letter on it. Write what is in the box on the blank next to the answer. Back Next

247. Back Home

249. Kristina saves her extra money to buy a pair of shoes for Christmas. Last week she saved Php. 82.60; two weeks ago, she saved Php. 100.05. This week she saved Php. 92.60. How much did she save in three weeks? Steps in Solving a Problem 1. Analyze the problem 2. What is asked? Total amount did Kristina save in three weeks. 3. What are the given facts? Php. 82.60, Php. 100.05, and Php. 96.10 Know Back Next

250. 3. What is the word clue? Save. What operation will you use? We use addition. 4. What is the number sentence? Php. 82.60 + Php. 100.05 + Php. 96.10 = N 5. What is the solution? Php. 82.60 Php. 100.05 + Php. 96.10 Php. 278.75 Solve Decide Show Back Next

251. Check 6. How do you check your answer? We add downward. Php. 82.60 Php. 100.05 + Php. 96.10 Php. 278.75 “ Kristina saves Php. 278.75 in three weeks.” Back Exercises It is easy to solve word problems by simply following the steps in solving word problem.

252. Worksheet I. Read the problem below and analyze it. A. Baranggay Maligaya is 28.5 km from the town proper. In going there Angelo traveled 12.75 km by jeep, 8.5 km by tricycle and the rest by hiking. How many km did Angelo hike? 1. What is asked? __________________________________________________________________________________________ 2. What are the given facts? __________________________________________________________________________________________ Back Next 20

253. 3. What is the process to be used? ______________________________________________________________________________________________ 4. What is the mathematical sentence? ______________________________________________________________________________________________ 5. How the solution is done? 6. What is the answer? ______________________________________________________________________________________________ Back Next

254. 7. How do you check the answer? B. Faye filled the basin with 2.95 liters of water. Her brother used 0.21 liter when he washed his hands and her sister used 0.8 liter when she washed her face. How much water was left in the basin? Back Next

255. 1. What is asked? __________________________________________________________________________________________ 2. What are the given facts? __________________________________________________________________________________________ 3. What is the process to be used? __________________________________________________________________________________________ 4. What is the mathematical sentence? __________________________________________________________________________________________ 5. How the solution is done? Back Next

256. 6. What is the answer? __________________________________________________________________________________________ 7. How do you check the answer? Back Next

257. C. Ron cut four pieces of bamboo. The first piece was 0.75 meter; the second was 2.278 meters; the third was 6.11 meters and the fourth was 6.72 meters. How much longer were the third and fourth pieces put together than the first and second pieces put together? 1. What is asked? __________________________________________________________________________________________ 2. What are the given facts? __________________________________________________________________________________________ Back Next

258. 3. What is the process to be used? ______________________________________________________________________________________________ 4. What is the mathematical sentence? ______________________________________________________________________________________________ 5. How the solution is done? 6. What is the answer? ______________________________________________________________________________________________ Back Next

259. 7. How do you check the answer? D. Pamn and Hazel went to a book fair. Pamn found 2 good books which cost Php. 45.00 and Php. 67.50. She only had Php.85.00 in her purse but she wanted to buy the books. Hazel offered to give her money. How much did Hazel share to Pamn? Back Next

260. 1. What is asked? __________________________________________________________________________________________ 2. What are the given facts? __________________________________________________________________________________________ 3. What is the process to be used? __________________________________________________________________________________________ 4. What is the mathematical sentence? __________________________________________________________________________________________ 5. How the solution is done? Back Next

261. 6. What is the answer? __________________________________________________________________________________________ 7. How do you check the answer? Back Next

262. E. Marlene wants to buy a bag that cost Php. 375.95. If she has saved Php. 148.50 for it, how much more does she need? 1. What is asked? __________________________________________________________________________________________ 2. What are the given facts? __________________________________________________________________________________________ 3. What is the process to be used? __________________________________________________________________________________________ Back Next

263. 4. What is the mathematical sentence? ______________________________________________________________________________________________ 5. How the solution is done? 6. What is the answer? ______________________________________________________________________________________________ 7. How do you check the answer? Back Home

264. UNIT IV MULTIPLICATION OF DECIMALS Content Next

265. OVERVIEW OF THE MODULAR WORKBOOK This modular workbook provides you with the understanding of the meaning of multiplication of decimals, multiply decimals in different form and how to estimate products. It will develop the ability of the students in multiplying decimal numbers. This modular workbook will help you to solve problems accurately and systematically. Back Next

266. OBJECTIVES OF THE MODULAR WORKBOOK After completing this Unit, you are expected to: 1. Define multiplication, multiplicand, multiplier, products and factors. 2. Know the ways of multiplying decimal numbers. 3. Learn the ways of multiplying decimal numbers involving zeros. 4. Learn how to make an estimate and know the ways of making estimates. Back Next

268. Multiplication is a short cut for repeated addition. It is a short way of adding the same decimal number. It is the inverse if division. Back Next .4 + .4 + .4 + .4 + .4 + .4 = 2.4 In multiplication, it is written as: .4 -> multiplicand x 6 -> multiplier 2.4 -> product (answer in multiplication) factors

269. The decimal numbers we multiply are called multiplicand and multiplier is the decimal number that multiplies. The answer in the multiplication is the product . The decimal numbers multiplied together are factors . Another examples: 9 0.08 1.24 0.007 x 0.5 x 3 x 2 x 4 4.5 0.24 2.48 0.028 Back Exercises

270. 1. What is multiplication? 2. What are factors? 3. What are products? 4. Give some examples of multiplication decimals. I. Give the meaning and explain the use of the following. Back Next 21 Worksheet

273. ____________ 1. The number we if multiply. ____________ 2. The numbers multiplied together. ____________ 3. The number that multiplies. ____________ 4. It is a short way of adding the same number of number times. ____________ 5. Multiplication is the inverse of _____________ Back Next

275. 4. 56.08 - ______ 9. 1.45 - ______ x 31.901 - ______ x 6.56 - ______ _______ - product ______ - product 5. 8.08 - multiplicand 10. 8.145 - multiplicand x 8.14 - multiplier x 6.001 - multiplier _____ -________ _____ -________ Back Home

277. Study these examples. Where do you place the decimal point in the product? 0.432 0.614 × 0.15 × 0.37 2160 4298 + 432 + 1842_ 0.06480 0.22718 Back Next

278. Remember: In multiplying decimals, the placement of the decimal point in the product is determined by the total number of decimal places in the factors. Count the number of decimal places from the right. To check, divide the product by either factors. Back Next

279. 6480 four digits 22718 five digits Add a zero to make Additional zeros is five decimal places in the product. not needed. 0.06480 0.2271 Additional Zero Add the decimal places in the factors. Then see how many decimal places the product has. Back Next 0.432 × 0.15 Five decimal places 0.614 × 0.37 Five decimal places

280. PRACTICE: Find the product by fill in the boxes for the correct answer. Back Next 0.3 0.2 0.4 0.1 0.5 0.6 0.4 0.7 0.3 0.5 0.4 0.3 0.7 0.6 0.8 0.4 0.2 0.1 0.5 0.4 0.3 0.7 0.6 0.8 0.4 0.2 0.1

281. Back Exercises 1.9 1.5 1.8 2.5 3.5 2.0 3.5 3.8 3.1 0.1 0.44 0.87 0.54 0.53 0.09 0.9 0.76 0.36 1.90 1.2 2.9 1.8 2.2 2.99 1.66 0.8 1.5 2.2 1.4 1.9 1.4 1.7 1.9 1.7 2.0 2.7 1.6 1.8 1.7 1.89 1.89 1.7 2.7 2.6 2.9

284. 4. 0.2547 x 0.2479 5. 0.3647 x 0.1248 Back Next

285. What did the big flower say about the little flower? FUN WITH MATH!!! To find the answer, write each of the following products in multiplying decimals. Back Next

286. __________ ___________ ___________ __________ 0. 7537344 0.0132 0.0003 0.08537832 ___________ ___________ 0.001445 0.290523 _________ __________ _________ ________ ________ 0.0000195 0.0044902 0.000492 0.05626725 0.0006 Back Home

288. Christopher can save Php. 18.65 in one month. How much money can he save in four months? 18.6 -> two decimal places x 4 74.60 Decimals are multiplied the same way as whole number. Back Next

289. Remember: In multiplying mixed decimals by whole numbers, count the decimal places in the mixed decimal to determine the placement of the decimal point in the product. Start counting the number of decimal places from the right. Back Next

290. Study other examples. 23.729 -> three decimal places x 47 166103 + 94916 1115.263 ↑ Partial product Back Next

291. 6.3572 -> four decimal places x 158 508576 317860 + 63572 1004.4376 ↑ Partial product Back Exercises

293. 4. 17.59 5. 48.723 6. 8.0035 × 83 × 52 × 179 + + 145997 2533596 + 14326265 Back Next

294. II. Find the product. 7. 934.04 8. 282.5601 9. 37.5852 × 251 x 49 × 784 10. 51.207 11. 4672.397 12. 693.3521 × 490 × 268 × 922 Back Next

295. 13. 75.373 14. 149.1811 15. 10.1496 x 44 x 1012 x 189 Back Home

297. What is the area of Ariel’s backyard if it is 12.932 m long and 8.45 m wide? NOTE: Area = length x width = 12.93m x 8.45m = 109.27540 sq.m² = m x m = m² 12.932 -> three decimal places × 8.45 -> two decimal places 64660 51728 + 103456 109.27540 -> five decimal places The backyard is 109.27540 square meters. Back Next

298. NOTE: Area = length x width = 12.93m x 8.45m = 109.27540 sq.m² = m x m = m² When multiplying mixed decimals by mixed decimals, the decimal point of the product is determined in this manner. Back Next

299. Decimal Decimal Decimal Places of first Places of second Places of Factor Factor the product Back Exercises

300. Worksheet I. Rewrite and arrange the partial products properly. Find the product and place the decimal points in the correct position. 1. 4.9526 2. 9.18234 × 3.215 × 75.68 247630 7345872 49526 5509404 99052 451170 + 148578 + 6427638 Back Next 25

301. 3. 57.6012 4. 2.01938 × 4.765 × 36.24 2880060 807752 3456072 403876 4032084 1211628 + 2304048 + 605814 Back Next

302. Find the product. 5. 15.6027 6. 92.46355 7. 8.932682 × 8.306 × 1.728 × 9.1865 8. 743.9516 9. 268.924 10. 5.1367 × 4.321 × 4.321 × 9.824 Back Home

304. Take a decimal, 0.7568. Multiply it by 10, by 100 and by 1,000. What are the products? Look at the following: 0.7568 0.7568 0.7568 × 10 × 100 × 1000 7.5680 75.6800 756.8000 Back Next

305. You see that the number of zeros contained in the factors 10, 100 and 1,000 tells how many places the decimal point in the other factor must be moved to the right to get the product. Examples: 10 × 0.75 = _______ 100 × 0.75 = _______ 1,000 × 0.75 = _______ Back Next

306. Observe: Move 1 place to the right. Move 2 place to the right. Move 3 place to the right. Back Exercises 750. 75. 7.5 0. 750 0. 75 0.75 0.750 0.75 0.75 0.75 × 1,000 × 100 × 10 Decimal

307. Worksheet Complete the following equations. 1. 3.67 × 10 = ______ 2. 100 × _____ = 4521 3. 1000 × _____ = 0.0049 4. _____ × 100 = 854.8 5. 2.918 × _____ = 2918 6. 35.66 × _____ = 35660 7. 0.0074 × _____ = 7.4 8. _____ × 10 = 0.163 9. 0.089 × 10 = _____ 10. _____ × 100 = 100.78 Back Next 25

308. II. Complete the table by multiplying each factor by 10, 100 and 1,000. Back Next

309. III. Multiply the following. Write your answers in the blanks provided: 1. 0.386 × 10 = ________ 2. 0.86 × 100 = ________ 3. 0.36 × 1000 = ________ 4. 0.473 × 1000 = ________ 5. 0.496 × 10 = ________ 6. 0.85 × 1000 = ________ 7. 0.7 × 1000 = ________ 8. 0.512 × 100 = ________ 9. 0.93 × 100 = ________ 10. 0.603 × 10 = ________ Back Home

312. 1. Rounding Method 4.52 × 6 27.12 Actual Value Rounded Value 5.00 × 6 30.00 2. Front End Method 4 .56 4.00 4. 5 2 .50 450 × 6 × 6 × 6 × 6 × 6 24.00 + 3.00 = 27.00 Back Next

313. The front – end method with adjustment is usually closer to the actual value. Back Exercises

315. 4. 38.721 5. 28.765 6. 75.814 × 3 × 9 × 13 7. 96.250 8. 18.263 9. 927.231 × 42 × 41 × 507 Back Next

316. 10. 36.287 11. 76.298 12. 28.183 × 206 × 304 × 543 Back Home

318. Example 1: A cone of ice cream costs Php. 16.25, how much in all did the 6 children spend for ice cream? Back Next

319. Example 2: What is the area of a rectangle with a length of 9.72 cm and width of 6.34 cm? Back Exercises

320. Worksheet Read, analyze and translate these problems to number sentence then solve. 1. Mrs. Hernandez baked 1,000 pineapple pies for a party of her daughter Kiana. If each pie costs Php. 17.85, how much did the 1,000 p