Precalculus (6th Edition)

RECALL: (1) The set of natural (or counting) numbers: $\left\{1, 2, 3, ...\right\}$ (2) The set of whole numbers : $\left\{0, 1, 2, 3, ....\right\}$ (3) The set of integers: $\left\{...-3, -2, 1, 0, 1, 2, 3, ...\right\}$ (4) Rational numbers are numbers that can be expressed as $\dfrac{p}{q}$ where $q\ne0$. (5) Irrational numbers are numbers that cannot be expressed as a quotient of two integers. (6) All the numbers described above are real numbers. From the descriptions above, $0$ is: an integer; a whole number; a rational number since it can be expressed as $\dfrac{0}{2}$; and a real number