1.1.5 Square Roots and Real Numbers (continued) Example 4 Classifying Real Numbers
Real numbers are all of the numbers on a number line. Every real number is either a rational number or an irrational number. A rational number can be written as a fraction where the numerator is an integer and the denominator is a nonzero integer. An irrational number cannot be written as such a fraction. Rational numbers that can be written with denominator of 1 are called integers, such as − 17, 0, and 4. The nonnegative integers are called whole numbers, and integers that are positive are called natural numbers. So, every natural number is also a whole number, an integer, and a rational number.
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