(In reply to
re: Hmmm... Computer by brianjn)
I found the same two solutions as did Charlie:
373 733
757 353
373 337
The condition "[t]he cells of a 3 x 3 grid contain prime digits" implies that each digit that makes up the 3digit prime must also be prime. Therefore the imposition made was by the poser's text of the problem. As the only digits that are prime are 2, 3, 5 and 7, the limit of digits is four.
Given the note following the posed problem, "[t]here are at least two other arrangements where a nonprime digit may be used, and digit totals are not always prime" offers a separate problem. If permitted the multiple occurance of the nonprime digit, there are several solutions available:
113 373 313 313 313 733
151 751 751 151 757 383
311 313 313 313 313 337
Edited on December 1, 2008, 9:41 pm

Posted by Dej Mar
on 20081201 21:32:35 