# 1.1 Numbers

**Real Number System • Number Line • Absolute Value • Signs of Inequality • Reciprocal • Denominate Numbers • Literal Numbers**

In technology and science, as well as in everyday life, we use the very familiar **counting numbers,** or **natural numbers** 1, 2, 3, and so on. The **whole numbers** include 0 as well as all the natural numbers. Because it is necessary and useful to use negative numbers as well as positive numbers in mathematics and its applications, the natural numbers are called the **positive integers**, and the numbers $\hspace{0.17em}-\hspace{0.17em}1\hspace{0.17em},\hspace{0.17em}\hspace{0.17em}-\hspace{0.17em}2\hspace{0.17em},\hspace{0.17em}\hspace{0.17em}-\hspace{0.17em}3\hspace{0.17em},\hspace{0.17em}$ and so on are the **negative integers.**

Therefore, *the* **integers** *include the positive integers, the negative integers*, and **zero,** *which is neither positive nor negative*. This means that the integers ...

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