Add and subtract positive and negative numbers
When adding and subtracting numbers it's important to be consistent with positive and negative values. Remember that two plus signs or two minus signs make a positive. One plus and one minus make a negative.
Adding and subtracting positive numbers
To add and subtract numbers always begin counting from zero.
When adding positive numbers, count to the right.
When subtracting positive numbers, count to the left.
Using a number line
Example
Calculate 4 - 5 - 3.
Imagine moving up and down a number line to get to the answer.
Starting from 0:
- count up to 4
- then subtract 5
- then subtract 3
The answer is -4.
- When adding positive numbers, count to the right.
- When subtracting positive numbers, count to the left.