Number Lines

A number line is a simple math tool. It is a straight line with numbers written on it. The numbers are spaced out evenly. Small numbers are on the left and bigger ones are on the right. Number lines help us add, subtract, and see how numbers work.

How to Use One

To add on a number line, start at the first number. Then jump to the right by how much you are adding. To subtract, jump to the left instead. For example, 3 plus 2 means starting at 3 and jumping right two times. You land on 5.

A number line bent into a circle so it has no beginning or end.
A number line bent into a circle so it has no beginning or end. (FastLearner444 / Wikimedia Commons)

Zero and Negative Numbers

Zero sits in the middle of many number lines. Numbers greater than zero go to the right. Numbers less than zero go to the left and are called negative numbers. Negative numbers have a minus sign in front, like -3. A number line helps us see how positive and negative numbers work together.

Fun Facts

  • Number lines can also show fractions and decimals between whole numbers.
  • Thermometers are a kind of number line that shows temperature.
  • The idea of negative numbers was used in China over 2,000 years ago.

Did You Know?

A number line can keep going forever in both directions, so it never really ends.