Divisible Tests

If a number ends with any of the digits 0, 2, 4, 6, or 8, you immediately say the number is divisible by 2. Why? We write any such number a as a = 10k + r, where r is the remainder when divided by 10. Hence r is one of the numbers 0, 2, 4, 6, 8. We know see that 10 is divisible by 2 and r is also divisible by 2. We conclude that 2 divides a.

Here are few more divisible tests with example and statements:

  1. Divisibility by 4
  2. Divisibility by 3 and 9
  3. Divisibility by 5 and 10
  4. Divisible by 11

 

Advertisements