# Divisibility

Explanation:

A number is divisible by another if the result of the division is an integer.

- A number is divisible by 2 if its last digit is 2, 4, 6, 8 or 0 (the number is then called even)
- A number is divisible by 3 if ist sum of digits is divisible by 3.
- A number is divisible by 4 if the number consisting of its last two digits is divisible by 4.
- A number is divisible by 5 if its last digit is a 5 or a 0.
- A number is divisible by 6 if it is divisible by 2 and 3, i.e. if it is even and its sum and digits is divisible by 3.
- A number is divisible by 8 if its last three digits are divisible by 8.
- A number is divisible by 9 if its sum of digits is divisible by 9.
- A number is divisible by 10 if ist last digit is a 0.
- A number is divisible by 12 if it is divisible by 3 and 4.
- A number is divisible by 15 if it is divisible by 3 and 5.
- A number is divisible by 18 if it is divisible by 2 and 9.
- A number is divisible by 20 if ist last digit is a 0 and the second last digit is even.

There are more divisibility rules, e.g. for 7 and 13, but they are not that easily done.