Nice table of Divisibility Rules from 2 to 13 from www.satmath4u.com

www.satmath4u.com

A number is divisible by:	If:
2	The last digit is even (0, 2, 4, 6, or 8).
3	The sum of the digits is divisible by 3.
4	The number formed by the last two digits of the original number is divisible by 4.
5	The number ending in a 0 or a 5.
6	The number is divisible by both 2 and 3.
7	The last digit of the number is multiplied by 2 and subtracted from the rest of the number and the answer is either 0 or divisible by 7.
8	The last three digits form a number divisible by 8.
9	The sum of the digits is divisible by 9.
10	The last digit is 0
11	You add every second digit and then subtract all other digits and the answer is zero or a multiple of 11.
12	The number is divisible by both 3 and 4.
13	You remove the last digit from the number, then subtract 9 times the deleted digit from the remaining number. If what is left is divisible by 13, then so is the original number.