Math for Computer Science

5 | Adding and subtracting negative numbers

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Examples
Practice Problems

Introduction

How are negative numbers added and subtracted?

Adding and subtracting negative numbers can be summarized with the following rules:

  • Adding a positive results in a move to the right on the number line
  • Adding a negative results in a move to the left on the number line
  • Subtracting a positive results in a move to the left on the number line
  • Subtracting a negative results in a move to the right on the number line

Examples

Adding negative numbers

Q: 5 + (-3)

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A: Adding negative 3 results in a move to the left on the number line. Thus, 5 + (-3) is the same as 5 − 3, or 2.


Subtracting negative numbers

Q: 5 − (-3)

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A: Subtracting negative 3 results in a move to the right on the number line. Thus, 5 − (-3) is the same as 5 + 3, or 8.

Practice | Adding and Subtracting Negative Numbers

Click "Create Report" upon completion of any practice set to document your progress: Example