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Is it, or is it not? (Posted on 2007-04-10) Difficulty: 4 of 5
Is (258+1)/5 an integer? A prime?

See The Solution Submitted by Federico Kereki    
Rating: 3.6667 (3 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
re(2): No Subject====error | Comment 4 of 12 |
(In reply to re: No Subject====error by Ady TZIDON)

You are correct in that I erred in my division.
288230376151711745 / 5 = 57646075230342349
= 107367629 536903681
therefore (258+1)/5 is not prime but composite.

All numbers of 2n + 1 are divisible by 5 where n is a positive integer and  n MOD 4 equals 2.

Edited on April 10, 2007, 8:10 pm
  Posted by Dej Mar on 2007-04-10 14:41:42

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