Rules for Adding and Subtracting Positive and Negative Integers
Addition Rules:
Positive + Positive = Positive sign, then add
Negative + Negative = Negative sign,
then add
5+4=9
(- 7) + (- 2) = - 9
(- 7) + 4 = -3
Positive + Negative = Sign of the larger
number then subtract
> the sign of the larger
number is (-)
> subtract 7-4 = 3
> -3
Additional Examples:
6 + (-9) = - 3
(- 3) + 7 = 4
5 + ( -3) = 2
Subtraction Rules:
(- 5) - 3 =
Negative - Positive = Negative
-5 + (-3) = -8
>change the subtraction
sign to an addition sign
> put a negative sign in
front of the second number
> think ‘plus a negative’
5 - (-3)
Positive - Negative = Positive + Positive =
Positive
5+3=8
>change the double
negative to an addition
sign
Negative - Negative = Negative + Positive =
( -5) + 3 =
> change the double
negative to a positive
( -5) + 3 = -2
>take the sign of the bigger
number and subtract
(-5) - (-3) =
>Use the sign of the larger number and
subtract
Additional Example:
(-3) – (-5) = (-3) + 5 = 2