I do it with , do it for .

A number is divisible by a number if and only if with .

It's obvious that .

So in your case you have that . That means that if was divisible by a number , it would necessarily be . We can try to check if it works : , which works.

I think what I did is not wrong...

Good luck. (All you have to do is to generalize what I did for the numbers for any number . I suggest you to check this : Division algorithm - Wikipedia, the free encyclopedia out.)