We use very little terminology in this book. Since some of this terminology is used in textbooks with slightly different meanings or different names, to avoid confusion, let use define what we mean.
An integer is one of the numbers
. . . ,−3, −2, −1, 0, 1, 2, 3, . . . Many books call thesewhole numbers. So 27 and−15 are integers, 2.7 is not.