Divisibility

  1. A number is divisible by 2 if the last digit is 0, 2, 4, 6, 8.
  1. A number is divisible by 3 if the sum of the digits is divisible by 3.
  1. A number is divisible by 4 if the last two digits make a number that is divisible by 4.
  1. A number is divisible by 5 if the last digit is 0 or 5.
  1. A number is divisible by 6 if the number is divisible by 2 and 3.
  1. Divisibility test for 7: Double the last number of the number. Then subtract that number from the remaining number ( the number without the one you just doubled). If that number is divisible by 7, then so is the original number you were testing. Ex. 357     Double the 7 and get 14. Subtract 14 from 35 and you get 21. 21 is divisible by 7 therefore so is 357.
  1. A number is divisible by 8 if the last three numbers make a number that is divisible by 8.
  1. A number is divisible by 9 if the sum of the digits is divisible by 9.
  1. A number is divisible by 10 if the last number is 0.