- Visual representation of the real numbers
- All real numbers can be plotted on a number line
- Numbers to the left of zero (0) on the line are negative numbers (-)
- Numbers to the right of zero (0) on the line are positive numbers (+)
- Numbers to the right of another number on the line are larger (0 is larger than every negative number , -1 is larger than -2, -1 > -2)
- The line is visually divided by negative integers and positive integers
- Numerically, the visual space between numbers on the line is the difference between the numbers (there are three spaces between 5 and 2, 5-2=3)
- The line indicates that there is no largest real number by the infinity symbol (∞)
- The line indicates that there is no smallest real number by the infinity symbol preceded by a negative symbol (-∞)
- With respect to the coordinate plane, the x-axis is a horizontal number line, and the y-axis is a vertical number line
- Applications: finding the sum of two integers, finding the difference between two integers, comparing two numbers