A number is divisible by:
2 if the last digit is even.
3 if the sum of the digits is divisible by 3.
4 if the last two digits form a number that is divisible by 4.
5 if the last digit is a 0 or 5.
6 if the number is divisible by both 2 & 3.
9 if the sum of the digits is divisible by 9.
10 if the last digit is a 0.
