Even numbers are integers that when divided by two produce another integer. Odd numbers are integers that are not divisible by two; in other words, when dividing an odd number by two, the result is not an integer.

Common examples of even numbers are zero, two, four, six and eight. Negative integers, such as -16 or -398 are also even numbers. Common examples of odd numbers are one, three, five, seven and nine, and negative numbers such as -11 or -255 are also considered odd.

Dividing an odd number by two results in a fraction that is halfway between two integers. For example, dividing 199 by two yields 99 1/2, which is halfway between 99 and 100. Adding two even numbers or two odd numbers together produces an even number. Adding an even and an odd number yields an odd number.