Odd number is a number that can not be divided by 2.

An even number is a number that can be divede by 2.

(a) The sum of two odd numbers is even;

For example –

3 + 5 = 8

7 + 11 = 18

13 + 19 = 32

(b) The sum of two even numbers is even;

Example-

2+6 = 8

8+10 = 18

16+16 = 32