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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?

  Submitted by brianjn    
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Solution: (Hide)
Originally I had considered a mix of Primes and Squares around the outside but it soon became very clear that adding Squares was a waste of effort.

From Spreadsheet analysis it also became very clear that the range of solutions was more extensive than I had managed manually.

I did assume that Charlie would present a computer listing which would glean all possible unique solutions. For those see Charlie's listings part 1 computer solution and added for part 2

Also check pcbouhid's comment re a powerful tool.

Comments: ( You must be logged in to post comments.)
  Subject Author Date
Puzzle ThoughtsK Sengupta2023-05-07 00:10:37
re(3): part 1 computer solutionDej Mar2009-07-12 15:26:16
re(2): part 1 computer solutionbrianjn2009-07-12 04:08:09
re: part 1 computer solutionDej Mar2009-07-12 02:07:23
re(3): Extensive === a powerful toolpcbouhid2009-07-11 22:47:25
re(2): Extensive === a powerful toolbrianjn2009-07-11 21:44:26
Solutionadded for part 2Charlie2009-07-11 14:14:01
Solutionpart 1 computer solutionCharlie2009-07-11 13:00:46
re: Extensive === a powerful toolpcbouhid2009-07-11 10:01:56
Extensivebrianjn2009-07-11 01:07:54
2 otherspcbouhid2009-07-11 00:29:28
Some solutionsDej Mar2009-07-10 13:24:37
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