1. The problem statement, all variables and given/known data If n>4 is a composite number, show that n|(n-1)! Conclude that (n-1)! not congruent -1(mod n). (This shows that Wilson's theorem can be used as a proof of primality. It is unfortunately not practical for large numbers) 2. Relevant equations 3. The attempt at a solution I know in words why a composite (ab) number does not work, but am not really sure how to prove it. Can anyone give me a jumping off point for this problem please?