Organic Name Reactions for the students and aspirants of Chemistry12th.pptx
Working Out Percentages Using Equivalent Fractions
1. How to Work Out the Percentage of
an Amount Using Equivalent
Fractions
e.g. 25% of 84
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3. A percentage (%) means: a part out of every
100.
So, 1% means: 1 part out of every 100. It is
equivalent (the same as) 1/100 and can be shown
in a diagram as:
4. To find 1% of a number, you can think of it as finding 1/100 of the number.
To find 1/100 of a number, you divide by 100 (the value of the denominator:
the number on the bottom of the fraction)
For example:
1% of 300 = 300 ÷ 100
=3
5. To find 1% of a number, you can think of it as finding 1/100 of the number.
To find 1/100 of a number, you divide by 100 (the value of the denominator:
the number on the bottom of the fraction)
For example:
1% of 300 = 300 ÷ 100
=3
1% of 900 = 900 ÷ 100
=9
6. To find 1% of a number, you can think of it as finding 1/100 of the number.
To find 1/100 of a number, you divide by 100 (the value of the denominator:
the number on the bottom of the fraction)
For example:
1% of 300 = 300 ÷ 100
=3
1% of 470 = 470 ÷ 100
= 4.70
1% of 900 = 900 ÷ 100
=9
7. To find 1% of a number, you can think of it as finding 1/100 of the number.
To find 1/100 of a number, you divide by 100 (the value of the denominator:
the number on the bottom of the fraction)
For example:
1% of 300 = 300 ÷ 100
=3
1% of 470 = 470 ÷ 100
= 4.70
1% of 900 = 900 ÷ 100
=9
1% of 675 = 675 ÷ 100
= 6.75
8. 10% means: 10 parts out of every 100. It is
equivalent (the same as) 10/100 or 1/10 and
can be shown in a diagram as:
9. To find 10% of a number, you can think of it as finding 1/10 of the number.
To find 1/10 of a number, you divide by 10 (the value of the denominator: the
number on the bottom of the fraction)
For example:
10% of 370 = 370 ÷ 10
= 37
10. To find 10% of a number, you can think of it as finding 1/10 of the number.
To find 1/10 of a number, you divide by 10 (the value of the denominator: the
number on the bottom of the fraction)
For example:
10% of 370 = 370 ÷ 10
= 37
10% of 9540 = 9540 ÷ 10
= 954
11. To find 10% of a number, you can think of it as finding 1/10 of the number.
To find 1/10 of a number, you divide by 10 (the value of the denominator: the
number on the bottom of the fraction)
For example:
10% of 370 = 370 ÷ 10
= 37
10% of 67 = 67 ÷ 10
= 6.7
10% of 9540 = 9540 ÷ 10
= 954
12. To find 10% of a number, you can think of it as finding 1/10 of the number.
To find 1/10 of a number, you divide by 10 (the value of the denominator: the
number on the bottom of the fraction)
For example:
10% of 370 = 370 ÷ 10
= 37
10% of 67 = 67 ÷ 10
= 6.7
10% of 9540 = 9540 ÷ 10
= 954
10% of 874 = 874 ÷ 10
= 87.4
13. 25% means: 25 parts out of every 100. It is
equivalent (the same as) 25/100 or 1/4 and
can be shown in a diagram as:
14. To find 25% of a number, you can think of it as finding 1/4 of the number.
To find 1/4 of a number, you divide by 4 (the value of the denominator: the
number on the bottom of the fraction)
For example:
25% of 36 = 36 ÷ 4
=9
15. To find 25% of a number, you can think of it as finding 1/4 of the number.
To find 1/4 of a number, you divide by 4 (the value of the denominator: the
number on the bottom of the fraction)
For example:
25% of 36 = 36 ÷ 4
=9
25% of 320 = 320 ÷ 4
= 80
16. To find 25% of a number, you can think of it as finding 1/4 of the number.
To find 1/4 of a number, you divide by 4 (the value of the denominator: the
number on the bottom of the fraction)
For example:
25% of 36 = 36 ÷ 4
=9
25% of 68 = 68 ÷ 4
= 17
25% of 320 = 320 ÷ 4
= 80
17. To find 25% of a number, you can think of it as finding 1/4 of the number.
To find 1/4 of a number, you divide by 4 (the value of the denominator: the
number on the bottom of the fraction)
For example:
25% of 36 = 36 ÷ 4
=9
25% of 68 = 68 ÷ 4
= 17
25% of 320 = 320 ÷ 4
= 80
25% of 44 = 44 ÷ 4
= 11
18. 50% means: 50 parts out of every 100. It is
equivalent (the same as) 50/100 or 1/2 and
can be shown in a diagram as:
19. To find 50% of a number, you can think of it as finding 1/2 of the number.
To find 1/2 of a number, you divide by 2 (the value of the denominator: the
number on the bottom of the fraction)
For example:
50% of 16 = 16 ÷ 2
=8
20. To find 50% of a number, you can think of it as finding 1/2 of the number.
To find 1/2 of a number, you divide by 2 (the value of the denominator: the
number on the bottom of the fraction)
For example:
50% of 16 = 16 ÷ 2
=8
50% of 320 = 320 ÷ 2
= 160
21. To find 50% of a number, you can think of it as finding 1/2 of the number.
To find 1/2 of a number, you divide by 2 (the value of the denominator: the
number on the bottom of the fraction)
For example:
50% of 16 = 16 ÷ 2
=8
50% of 48 = 48 ÷ 2
= 24
50% of 320 = 320 ÷ 2
= 160
22. To find 50% of a number, you can think of it as finding 1/2 of the number.
To find 1/2 of a number, you divide by 2 (the value of the denominator: the
number on the bottom of the fraction)
For example:
50% of 16 = 16 ÷ 2
=8
50% of 48 = 48 ÷ 2
= 24
50% of 320 = 320 ÷ 2
= 160
50% of 11 = 11 ÷ 2
= 5.5
23. 75% means: 75 parts out of every 100. It is
equivalent (the same as) 75/100 or 3/4 and
can be shown in a diagram as:
24. To find 75% of a number, you can think of it as finding 3/4 of the number.
To find 3/4 of a number, you divide by 4 (the value of the denominator: the
number on the bottom of the fraction) and multiply by 3 (the value of the
numerator: the number on the top of the fraction)
For example:
75% of 16 = (16 ÷ 4) x 3
= 12
25. To find 75% of a number, you can think of it as finding 3/4 of the number.
To find 3/4 of a number, you divide by 4 (the value of the denominator: the
number on the bottom of the fraction) and multiply by 3 (the value of the
numerator: the number on the top of the fraction)
For example:
75% of 16 = (16 ÷ 4) x 3
= 12
75% of 32 = (32 ÷ 4) x 3
= 24
26. To find 75% of a number, you can think of it as finding 3/4 of the number.
To find 3/4 of a number, you divide by 4 (the value of the denominator: the
number on the bottom of the fraction) and multiply by 3 (the value of the
numerator: the number on the top of the fraction)
For example:
75% of 16 = (16 ÷ 4) x 3
= 12
75% of 48 = (48 ÷ 4) x 3
= 36
75% of 32 = (32 ÷ 4) x 3
= 24
27. To find 75% of a number, you can think of it as finding 3/4 of the number.
To find 3/4 of a number, you divide by 4 (the value of the denominator: the
number on the bottom of the fraction) and multiply by 3 (the value of the
numerator: the number on the top of the fraction)
For example:
75% of 16 = (16 ÷ 4) x 3
= 12
75% of 48 = (48 ÷ 4) x 3
= 36
75% of 32 = (32 ÷ 4) x 3
= 24
75% of 44 = (44 ÷ 4) x 3
= 33
28. To work out other percentages, you can build
them up from the percentages that you know.
Remember:
1% = 1/100
10% = 1/10
25% = ¼
50% = ½
75% = 3/4
29. To work out other percentages, you can build
them up from the percentages that you know.
For example, to find out 20% of 40:
20% = 10% x 2
10% of 40 = 4
20% of 40 = 4 x 2
=8
Remember:
1% = 1/100
10% = 1/10
25% = ¼
50% = ½
75% = 3/4
30. To work out other percentages, you can build
them up from the percentages that you know.
For example, to find out 20% of 40:
20% = 10% x 2
10% of 40 = 4
20% of 40 = 4 x 2
=8
To find out 40% of 50:
40% = 10% x 4
10% of 50 = 5
40% of 50 = 5 x 4
= 20
Remember:
1% = 1/100
10% = 1/10
25% = ¼
50% = ½
75% = 3/4
31. To work out other percentages, you can build
them up from the percentages that you know.
For example, to find out 20% of 40:
20% = 10% x 2
10% of 40 = 4
20% of 40 = 4 x 2
=8
To find out 40% of 50:
40% = 10% x 4
10% of 50 = 5
40% of 50 = 5 x 4
= 20
To find out 60% of 90:
60% = 10% x 6
10% of 90 = 9
60% of 90 = 9 x 6
= 54
Remember:
1% = 1/100
10% = 1/10
25% = ¼
50% = ½
75% = 3/4
32. To find out 35% of 60:
35% = 10% + 25%
10% of 60 = 6
25% of 60 = 15
35% = 6 + 15
= 21
Remember:
1% = 1/100
10% = 1/10
25% = ¼
50% = ½
75% = 3/4
33. To find out 35% of 60:
35% = 10% + 25%
10% of 60 = 6
25% of 60 = 15
35% = 6 + 15
= 21
To find out 65% of 80:
65% = 75% - 10%
75% of 80 = 60
10% of 80 = 8
65% = 60 – 8
= 52
Remember:
1% = 1/100
10% = 1/10
25% = ¼
50% = ½
75% = 3/4
34. To find out 35% of 60:
35% = 10% + 25%
10% of 60 = 6
25% of 60 = 15
35% = 6 + 15
= 21
To find out 65% of 80:
65% = 75% - 10%
75% of 80 = 60
10% of 80 = 8
65% = 60 – 8
= 52
To find out 12% of 90:
12% = 10% + (1% x 2)
10% of 90 = 9
2% of 90 = 0.9 x 2 = 1.8
12% = 9 + 1.8
= 10.8
Remember:
1% = 1/100
10% = 1/10
25% = ¼
50% = ½
75% = 3/4
35. To find out 35% of 60:
35% = 10% + 25%
10% of 60 = 6
25% of 60 = 15
35% = 6 + 15
= 21
To find out 65% of 80:
65% = 75% - 10%
75% of 80 = 60
10% of 80 = 8
65% = 60 – 8
= 52
To find out 12% of 90:
12% = 10% + (1% x 2)
10% of 90 = 9
2% of 90 = 0.9 x 2 = 1.8
12% = 9 + 1.8
= 10.8
Remember:
1% = 1/100
10% = 1/10
25% = ¼
50% = ½
75% = 3/4
It’s just a question of building
up the right combination.
36. That’s it for now......
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