Here is your cheat sheet to help you remember what to do with positive and negative numbers
(integers) when adding, subtracting, multiplying or dividing.
1. Adding Rules: SAME SIGN SUM (if they have the same sign, add the #’s together)
DIFFERENT SIGN DIFFERENCE (if different signs, find difference of #’s and
keep the sign of the # with the larger absolute value)
SAME SIGN: 5 + 4 = 9
(- 7) + (- 2) = - 9
-6 + -2 = -8
DIFFERENT SIGN (Sum of a negative and a positive number):
Think Subtraction then use the sign of the # with the larger absolute value
(-7) + 4 = -3
2.
(-3) + 7 = 4
6 + (-9) = -3
5 + (-3) = 2
Subtracting Rules: REMEMBER: KEEP, CHANGE, CHANGE
Keep first number the same, Change operation to addition,
then change the second number to its Opposite value
(- 5) - 3 = -5 + (-3) = -8
5 - (-3) = 5 + 3 = 8
4 – (-9) = 4 + (+9) = 13
(-7) – 3 = (-7) + (-3) = -10
(-12) – (-8) = (-12) + (+8) = -4
(Change double negatives to a positive)
(-5) - (-3) = ( -5) + 3 = -2
(-3) - ( -5) = (-3) + 5 = 2
3. Multiplying & Dividing Rules: (If the signs are the same, the answer is positive. If the
signs are different, the answer is negative.)
Pos x Pos = Positive:
Neg x Neg = Positive:
Neg x Pos = Negative:
Pos x Neg = Negative:
3x2=6
(-2) x (-8) = 16
(-3) x 4 = -12
3 x (-4) = -12
Pos ÷ Pos = Positive: 12 ÷ 3 = 4
Neg ÷ Neg = Positive: (-12) ÷ (-3) = 4
Neg ÷ Pos = Negative: (-12) ÷ 3 = -4
Pos ÷ Neg = Negative: 12 ÷ (-3) = -4