1: Everything is divisible by 1.
2: All even numbers are divisible by 2.
3: The sum of the digits are divisible by 3.
4: The last two digits must be divisible by 4.
5: The number must end in a 5 or 0.
6: The number must be divisible by 2 and 3.
7: Multiply the number of tens by 3 and add the ones digit.
8: The last three digits must be divisible by 8.
9: The sum of the digits must be divisible by 9.
10: The last digit must be a 0.
11: Take the one's digit and multiply it by 10. Add the number of tens. The result must be a multiple of 11.
12: The number must be divisible by 3 and 4.
2: All even numbers are divisible by 2.
3: The sum of the digits are divisible by 3.
4: The last two digits must be divisible by 4.
5: The number must end in a 5 or 0.
6: The number must be divisible by 2 and 3.
7: Multiply the number of tens by 3 and add the ones digit.
8: The last three digits must be divisible by 8.
9: The sum of the digits must be divisible by 9.
10: The last digit must be a 0.
11: Take the one's digit and multiply it by 10. Add the number of tens. The result must be a multiple of 11.
12: The number must be divisible by 3 and 4.