A number which is not divisible by 2  is called an odd number. An odd number always ends in 1, 3, 5, 7, or 9. Examples of odd numbers: 51 , " 543 , 8765 , " 97 , 9 , etc. An odd number is always 1 more than (or 1 less than) an even number.

If a number divided by 2 leaves a remainder of 1, then the number is odd. You can check for this using num % 2 == 1 .