**Use number linesĀ **

A good way to get a picture of a set

of numbers is by using a **number line. **To construct a number line, choose

any point on a horizontal line and label it 0. Next, choose a point to the right

of 0 and label it 1. The distance from 0 to 1 establishes a scale that can be

used to locate more points, with positive numbers to the right of 0 and negative

numbers to the left of 0. The number 0 is neither positive nor negative.

A number line is shown in Figure 1.

The set of numbers identified on the number line in Figure 1, including

positive and negative numbers and 0, is part of the set of **integers, **written

** I **5

**{. . . ,**2

**3,**2

**2,**2

**1, 0, 1, 2, 3, . . . }**.

Each number on a number line is called the **coordinate **of the point that

it labels, while the point is the **graph **of the number. Figure 2 shows a number

line with several selected points graphed on it.