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Help for another trouble

  1. Oct 14, 2007 #1
    If n is composite, n>4, prove that (n-1)!= 0 (mod n). = is congruent
     
  2. jcsd
  3. Oct 14, 2007 #2
    Let n=(n-i)(n-j). If i is not equal to j then both terms will appear in the expansion of (n-1)!. You can probably handle the case i=j yourself with a little thought.
     
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