Adding
Subtracting
Multiplying
Dividing
Rules
100

(-10) + 17 =

7

100

387-258 =

129

100

(-7) x 4 =

-28

100

(-24) ÷ 8 =

-3

100

adding positive and negative number rules

- + - = - Combine the addends - sum has the same sign as both addends

+ + + = + Combine the addends - sum has the same sign as both addends

- + + = find the difference - whichever addend has the greater absolute value determines the sign of the sum

+ + - + find the difference - whichever addend has the greater absolute value determines the sign of the sum

200

(-32.5) + (-25.37) =

-57.87

200

25 - (-15) =

40

200

(-6) x (-9) =

54

200

(-42) ÷ (-6) =

7

200

Subtracting positive and negative number rules

Steps to follow

1. Turn the subtraction problem into an addition problem using the additive inverse. 

2. Follow the rules of adding positive and negative numbers.

300

(-102)+ 53.9 = 

-48.1

300
(-12.5) - (-13.7) = 

1.2

300

(-3.5) x (-0.7) =

2.45

300

(-25.5) ÷ (-5) =

5.1

300

Multiplying positive and negative numbers

- x + = -

- x - = +

400

(-3/5) + (-2/15) = 

-11/15

400

(-42.87) - 13.19 = 

-56.06

400

25.4 x (-18) = 

-457.2

400

(-3/4) ÷ (-8/9) = 

27/32

400

Dividing positive and negative numbers 

- ÷ - = +

- ÷ + = -

+ ÷ - =- 

+ ÷ + = +

500

(-17/20) + 1/4 = 

-12/20 or simplified -6/10
500

(-1/4) - 7/8 =

-9/8 or -1 1/8

500

(-3/9) x (-5/6) = 

15/54 or 5/18

500

2/7 ÷ 3 1/4 = 

8/91

500

decimals and fractions 

adding: 

When adding fractions convert fractions so, both terms have the same denominator

When adding decimals align you terms place values

Subtracting:

When subtracting fractions convert fractions so, both terms have the same denominator

When subtracting decimals align you terms place values

Multiplying:

When multiplying fractions multiply straight across the numerators and straight across the denominators 

When multiplying decimals your product will have as many decimal places as the total decimal places in both of your factors

Dividing:

When dividng fractions multiply by the reciprocal of the divisor

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