REAL NUMBERS, R

1. Integers, Z

The integers are those real numbers

                            …, -3, -2, -1, 0, 1, 2, 3,…

We denote the integers by Z; hence we can write

                            Z = { …, -2, - 1, 0, 1, 2,…}

The integers are also referred to as the “whole” numbers.

One important property of the integers is that they are “closed” under the operations of addition, multiplication and subtraction; that is, the sum, product and difference of two integers is again in integer. Notice that the quotient of two integers, e.g. 3 and 7, need not be an integer; hence the integers are not closed under the operation of division.