[MOVED] Number Theory: If (n-1)!(mod n) value is known....

[mooshupork34]

If you know the value of (n-1)! (mod n), then how can you use this value to find out whether n is prime or composite?

 

[pka]

This all falls in the area of Wilson's Theorem.
http://mathworld.wolfram.com/WilsonsTheorem.html