How to tell if a number is divisible by another number?

We have some rules about that:
1. n is divisible by 2, so it has to end by an even number such as 0, 2, 4, 6, 8.
2. n is divisible by 3, so the sum of its digits is a number divisible by 3
3. n is divisible by 5,  so it has to end by 0 or 5.
4. n is divisible by 4, so its two last digits forming a number divisible by 4 like 212, 304
5. n is divisible by 9, so the sum of its digits is a number divisible by 9
6.  n is divisible by 10,   so it has to end by 0.
and there are some other rules like if n is divisible by 2 and 3, so it is divisible by 6