If the _____ of all digits of a number is divisible by 3 then the number is divisible by 3.
If the _____ of all digits of a number is divisible by 3 then the number is divisible by 3.
Explanation
If the sum of all digits of a number is divisible by 3, then the number itself is divisible by 3.
This is a divisibility rule for 3.