DIVISIBILITY RULES WORKSHEET - onlinemath4all.com According to the divisibility rule for 3, if the sum of all the digits is divisible by 3 or a multiple of 3, then the number is divisible by 3. Add all the digits in the number 252. 2 + 5 + 2 = 9. The sum of the digits in the given number 252 is 9 which is a multiple of 3. So, 252 is divisible by 3. Answer 3 :