Adding and subtracting negative numbers
A number line can be used to add and subtract negative numbers.
Adding with negative numbers
Example
What is \(-4 + 5\)?
To add -4 and 5, draw the starting number on a number line and count to the right when adding positive numbers.
So, \(-4 + 5 = 1\)
Subtracting with negative numbers
Example
What is \(-2 - 2\)?
To subtract 2 from -2, start at -2 on a number line, and count to the left when subtracting positive numbers.
\(-2 - 2 = -4\)
Example
What is the difference in temperature between a desert at 40 掳C and a mountain top at -2 掳C?
\(40 - (-2) = 42\), so the difference in temperature between the desert and the mountain top is 42 掳C.
Example
What is \(4 - (-2)\)?
To subtract -2 from 4, start at number 4 on a number line, and count to the right. So, \(4 - (- 2) = 6\).