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Primes Around a Square (Posted on 2009-07-10) Difficulty: 2 of 5
A B C
D   E
F G H

The letters A-H are different digits from 1 to 9.

Read from left to right and top down, the four numbers formed are primes.

There is not just one solution. (Flipping along the diagonal A-H does not present a different solution).

Suppose "0" is allowed, and A cannot have that value, what other unique solutions are available?

See The Solution Submitted by brianjn    
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re: Extensive === a powerful tool | Comment 4 of 12 |
(In reply to Extensive by brianjn)

Recently I found a site which deals with crossnumbers, www.crossnumber.com, owned by Rainer Typke. Using it one can solve various types of puzzles involving prime numbers, matrices, Fibonacci numbers, squares, etc... even cryptarithmetic puzzles.

This one particularly I solved there, and the grid and the code (very easy) can be found clicking in the link "find more puzzles", then "Primes 3x3 - pcbouhid".

Iīm not going to list here all the solutions it was found disallowing or allowing the "zero", though I didnīt remove those that possibly are the same "fliping along the diagonals". One can see all there.



Edited on July 11, 2009, 10:59 am
  Posted by pcbouhid on 2009-07-11 10:01:56

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