Find all numbers that are invertible in a certain set.

Question

So the question goes like this:

Determine all invertible numbers in $$ {Z}_{24}$$

I know that a invertible number in a certain set is an integer that multiplied with a certain other integer in the set is equal to 1.

But I don't know how to find all numbers!

Any hint you could give me? A small push in the right direction.

Answer 1

By Bézout's identity it is all the numbers coprime to $24$