Arithmetic/The Number Line

An example of a number line. Notice the arrows indicating that the line goes infinitely in both directions.

The number line is a one-dimensional graph to show the relative positions of numbers. As the line goes left, the numbers have less value; as the line goes right, the numbers have more value. The line continues infinitely (without end) in both directions.

A number line in intervals of ten

The number line can be made in different intervals, that is, how many numbers the graph goes up and down by. The top image shows a number line going in intervals of one, while the bottom line graph goes in intervals of ten.

Absolute Value

As you can see, the positive and negative numbers are of equal distance from the number zero. The distance of a number from zero is called the absolute value. The absolute value of a number is always positive or zero. This may also be referred to as the magnitude of the number. It is represented by two lines on the left and right of a number. When solving problems with absolute values, always solve the absolute number first. For example:

$|-5|=5$
$|0|=0$
$|5+3|=|8|=8$
$36-|-55|=36-55=-19$