What is a number line?

A number line is a straight line that graphically represents real numbers as a series of points whose distance from an origin or "zero point" is proportional to their value. The line is useful for addition, subtraction and showing relations between numbers in basic mathematics.

The marked points on the line represent integers and have even spacing in between.

The number zero divides the number line into two symmetric halves. Positive numbers lie on the right side of zero, and negative numbers are on the left side. Arrows appear on both ends of the line, indicating that the line continues indefinitely.