Which of these numbers is not an integer?

A. - 1

B. 0

C. 1/2

D. 1

An integer is a whole number that can be counted. An example scale is

-5, - 4, - 3, - 2, - 1, 0, 1, 2, 3, 4, 5,

An integer does not include fractions/decimals. The only number that is not an integer is C because A, B, and D are all on the integer scale.