1. The problem statement, all variables and given/known data 16!x is congruent to 5 (mod 17). Find x. 2. Relevant equations 3. The attempt at a solution I am not sure if I have the answer correct, but I would like to know if I am following rules of modular arithmetic correctly. According to Wilson's Theorem, (p-1)! + 1 is congruent to 0 mod(p) where p is prime. So can I say for this problem since (17-1)! + 1 is congruent to 0 (modp) -> move the one to the other side of congruence to get 16! congruent to -1 (mod p) and multiply both sides of the congruence by -5, requiring x = -5?