Is your child having problems remembering when to use a positive or negative sign? Check out these easy rules…

How To Know When to use a Positive and Negative Number                               

By Deb Russell, About.com Guide

1. Adding Rules:

Positive + Positive = Positive: 5 + 4 = 9
Negative + Negative = Negative: (- 7) + (- 2) = - 9

Sum of a negative and a positive number: Use the sign of the larger number and subtract

(- 7) + 4 = -3
6 + (-9) = - 3
(- 3) + 7 = 4
5 + ( -3) = 2

2. Subtracting Rules:

Negative - Positive = Negative: (- 5) - 3 = -5 + (-3) = -8
Positive - Negative = Positive + Positive = Positive: 5 - (-3) = 5 + 3 = 8
Negative - Negative = Negative + Positive = Use the sign of the larger number and subtract (Change double negatives to a positive)
(-5) - (-3) = ( -5) + 3 = -2
(-3) - ( -5) = (-3) + 5 = 2

3. Multiplying Rules:

Positive x Positive = Positive: 3 x 2 = 6
Negative x Negative = Positive: (-2) x (-8) = 16
Negative x Positive = Negative: (-3) x 4 = -12
Positive x Negative = Negative: 3 x (-4) = -12

4. Dividing Rules:

Positive ÷ Positive = Positive: 12 ÷ 3 = 4
Negative ÷ Negative = Positive: (-12) ÷ (-3) = 4
Negative ÷ Positive = Negative: (-12) ÷ 3 = -4
Positive ÷ Negative = Negative: 12 ÷ (-3) = -4

Tips:

1. When working with rules for positive and negative numbers, try and think of weight loss or poker games to help solidify 'what this works'.

2. Using a number line showing both sides of 0 is very helpful to help develop the understanding of working with positive and negative numbers/integers.