Tests for Divisibility

Division can be performed to see if one number is a factor of another, but there are shortcuts:

  • A number is divisible by 2 if the final digit is a multiple of 2 (e.g. 0, 2, 4 etc). E.g. 184, 2098 and 380.
  • A number is divisible by 3 if the sum of the digits is a multiple of 3 (e.g. 3, 6, 9 etc). E.g. 573, 903 and 39 (5 + 7 + 3 = 15, 9 + 0 + 3 = 12 and 3 + 9 = 12).
  • A number is divisible by 5 if the final digit is either zero or 5. E.g. 80, 3665 and 380.

There are many other tests for divisibility, but these are the most frequently used.

Task17