deletions | additions       diff --git a/p7.tex b/p7.tex  index 496aa8d..12116ed 100644  --- a/p7.tex  +++ b/p7.tex 
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Clearly, $n$ can divide $(n-1)!$, so it always be $0\ \textrm{mod}\ n$ instead of $-1\ \textrm{mod}\ n$    Example:     $8! \equiv x\ \textrm{mod}\ 9$     For some a, $3*6*a = 8!$. It will always yield 0 modulo n.   \end{itemize}