Because p is prime by wilson theorem p | (p-1)!+1
Or p^2| (p! + p)
or p^2| (p! + p) (p+1)
Or p^2| (p+1)! + p(p+1)
or (p+1)! \equiv -p(p+1) \pmod p^2
So fractional part of \frac{(p+1)!}{p^2} is same as fractional part of \frac{-p(p+1)}{p^2} or is \frac{p-1}{p}
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