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From: crobbins@Cs.Ucl.AC.UK (Colin J Robbins)
Newsgroups: comp.lang.pascal
Subject: Perfect number program
Message-ID: <9657@brl-adm.ARPA>
Date: Wed, 7-Oct-87 05:19:03 EDT
Article-I.D.: brl-adm.9657
Posted: Wed Oct  7 05:19:03 1987
Date-Received: Sat, 10-Oct-87 07:37:53 EDT
Sender: news@brl-adm.ARPA
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  For a start you could remove 2 of the divides in the inner loop like thus:

  FOR I=2 TO 10000 DO
      BEGIN
      W = 0;
      D = I/K;
      FOR K=2 TO I DO
          IF D = TRUNC (D) THEN W=W+(D)
      IF W=I THEN PRINT W "IS A PERFECT NUMBER"
      END        

  This should have approximately a 3 fold increse in speed.

  Secondly, you could write a more inteligent routin altogether that
  take account of the factors tried before, for example, if 2 was not
  a factor then it is pointless trying 4,6,8 etc to see if the are
  factors.

  The routine for this - left as an exercise for the reader !!!            

  Colin Robbins
  
  University College, London
  England.