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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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Comments: ( Back to comment list | You must be logged in to post comments.)
re: part 1 computer solution | Comment 9 of 12 |
(In reply to part 1 computer solution by Charlie)

As nearly always, Charlie, you are very thorough.
I would like to comment on your statement --
"If any had 6 primes (using the middle rows) those would have been flagged via an asterisk, but none were.". As all 2+digit primes end in either 1, 3, 7 or 9 -- one of four distinct digits -- then using the middle row to find six primes is indeed impossible as there would need be for five distinct digits to end the primes: C, E, F, G and H.
  Posted by Dej Mar on 2009-07-12 02:07:23

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