What is a number line ? Definition and examples.

A number line is a line, ray, or line segment on which every point is assigned a real number.

Number lines


Above, you can see three number lines.

  • A line on which every point has been assigned a real number

  • A segment on which every point has been assigned a real number.

  • Finally, a ray on which every point has been assigned a real number.

Notice that although one of the number lines is made with a segment, it does not have just four points. There are lots of points between 1 and 2, 2 and 3, and 3 and 4. Similarly, there are lots of points between the numbers that you see for the ray and the line.

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