Even numbers from 0 to 30:

0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30

Odd numbers form 0 to 30:

1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29

Notice that all of the even numbers end with 0, 2, 4, 6, or 8.
All of the odd numbers end with 1, 3, 5, 7, or 9.