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$m$ is a positive integer, and $ m > 1$,
Prove that if $(m - 1)! + 1$ is divisible by $m$, $m$ is a prime.

Solve this by making a contradiction.
My english isn't so well. Please help and thank you for your attention :)

  • 1
    The converse is also true; see [Wilson's Theorem](http://en.wikipedia.org/wiki/Wilson's_theorem).2012-09-04

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