Even numbers can be divided evenly into groups of two. The number four can be divided into two groups of two.
Odd numbers can NOT be divided evenly into groups of two. The number five can be divided into two groups of two and one group of one.
Even numbers always end with a digit of 0, 2, 4, 6 or 8. 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30 are even numbers.
Odd numbers always end with a digit of 1, 3, 5, 7, or 9. 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31 are odd numbers.
1Odd 2Even 3Odd 4Even 5Odd 6Even 7Odd 8Even 9Odd 10Even 11Odd 12Even 1Odd 3Odd 5Odd 7Odd 9Odd 11Odd 2Even 4Even 6Even 8Even 10Even 12Even