Subtract the smallest number
from the largest number and
add 1, divide by 2.
COUNTING CONSEC.
EVEN/ODD INTEGERS
If the result is not an integer number,
see how the series starts and ends.
DIVISIBILITY FACTS
1 is a factor/divisor of every integer.
0 is a multiple of every integer.
The factors of an integer include
positive and negative integers.
NUMBER OF DIVISORS
60 = 22 31 51 = 60
1 x 60
2 x 30
3 x 20
4 x 15
5 x 12
6 x 10 3 x 2 x 2 = 12
• Take all the exponents from the
prime factorization and add 1 to
each of them.
• Multiply the modified exponents
together.
of two integers is the
largest positive integer that
divides the numbers
without a remainder.
DIVISIBILITY BY 6
72 7+2 = 9
1200 1+2+0+0 = 3
1860 1+8+6+0 = 15
Sum of the digits is multiple
of 3 and the last digit is even
DIVISIBILITY BY 7
3101 310 – 2 = 308
308 30 – 16 = 14
Take the last digit off the
number, double it and
subtract the doubled number
from the remaining number
DIVISIBILITY BY 9
729 7+2+9 = 18
810 8+1+0 = 9
9918 9+9+1+8 = 27
Sum of digits is a multiple of 9
Divisibility Rules
A number is divisible by … Divisible
Not
Divisible
2 If the last digit is even 3,728 357
3 If the sum of the digits is a multiple of 3 120 155
4 If the last two digits form a number divisible by 4 144 142
5 If the last digit is 0 or 5 150 123
6 If the number is divisible by both 2 and 3 48 20
9 If the sum of the digits is divisible by 9 729 811
10 If the last digit is 0 50 53
2 7
15 15
Make sure the
denominators
are the same.
Add the
numerators, put
the answer over
the denominator.
Simplify the
fraction.
ADDING FRACTIONS
9
15
3
5
Make sure the
denominators
are the same.
Subtract the
numerators. Put the
answer over the
same denominator.
Simplify the
fraction.
SUBTRACTING
FRACTIONS
2 9 1
15 10 5
25
30
4 27 6
30
4 27 6
30 30 30
5
6
1 3
2 5
Turn the second
fraction upside-down
(this is now a
reciprocal).
Multiply the first
fraction by that
reciprocal.
Simplify
the
fraction.
DIVIDING FRACTIONS
1 5
2 3
1 5
2 3
5
6
2
2
3
Distribute the
exponent into the
numerator as well as
into the denominator.
Evaluate the
numerator
and the
denominator.
Simplify
the
fraction.
POWER OF FRACTIONS
2
2
2
3
4
9
4
9
Distribute the root
into the
numerator as
well as into the
denominator.
Evaluate the
numerator
and the
denominator.
Simplify
the
fraction.
ROOTS OF FRACTIONS
4
9
2
3
Multiply the
whole number
part by the
denominator
Add the
numerator
The result is the
new numerator
(over the same
denominator)
2
5
7
MIXED NUMBER TO
IMPROPER FRACTION
5 7 2
7
37
7
Divide the denominator
into the numerator.
The quotient becomes
the whole number.
The remainder becomes
the new numerator.
7
2
IMPROPER FRACTION
TO MIXED NUMBER
1
3
2
Write down
the decimal
divided by 1.
Multiply both top
and bottom by 10
for every number
after the decimal
point.
Simplify (or
reduce) the
fraction.
DECIMAL TO FRACTION
0.75
0.75 100
1 100
75
100
3
4
It is not necessary
to align the
decimal points.
Add the number of digits to the
right of the decimal points in the
decimals being multiplied.
MULTIPLYING
DECIMALS
Move the decimal
point in the divisor to
the right until the
divisor becomes an
integer.
Move the
decimal point in
the dividend the
same number of
places.
Proceed
with the
division.
DIVIDING DECIMALS
COMBINED PERCENT
INCREASE
A price went up 10% one year, and the
new price went up 20% the next year.
What is the combined percent
increase?
32% increase
110 120
100 132
100 100
COMBINED PERCENT
DECREASE
A price went down 10% one year, and
the new price went down 20% the next
year. What is the combined percent
decrease?
28% decrease
90 80
100 72
100 100
COMBINED PERCENT
INC/DEC
A price went down 20% one year, and
the new price went up 10% the next
year. What is the combined percent
decrease?
12% decrease
80 110
100 88
100 100
1
I P r n
F P I
F P rn
Simple interest (I) is determined
by multiplying the interest rate (r)
by the principal (P) by the
number of periods (n).
SIMPLE INTEREST
SIMPLE INTEREST
Carine deposits $ 1,000 into a special bank account
which pays a simple annual interest rate of 5% for 3
years. How much will be in her account at the end of the
investment term?
P = 1,000
r = 5% = 0.05
n = 3
1
1,000 1 0.05 3
1,150
F P rn
F
F
5
5% 1,000 1,000 50
100
of
SIMPLE INTEREST
5
5% 1,000 1,000 50
100
of
5
5% 1,000 1,000 50
100
of
Simple Interest on 1,000.00 after:
Interest (I) calculated on the initial
principal (P) and also on the
accumulated interest of previous
periods of a deposit or loan.
1
n
F P r
I F P
COMPOUND INTEREST
COMPOUND INTEREST
Carine deposits $ 1,000 into a special bank account
which pays a compound annual interest rate of 5% for 3
years. How much will be in her account at the end of the
investment term?
P = 1,000
r = 5% = 0.05
n = 3
3
1
1,000 1 0.05
1,157.625
n
F P r
F
F
COMPOUND INTEREST
5
5% 1,000.00 1,000.00 50.00
100
of
5
5% 1,050.00 1,050.00 52.50
100
of
5
5% 1,102.50 1,102.50 55.13
100
of
Compound Interest on 1,000.00 after: