Fashion a square to house all nine prime numbers
We know of course that the perimeter digits must always be chosen from the set 1,3,7 and 9, since all primes end this way. Here is Tom's solution:
The nine primes are: 113 151 157 179 311 359 751 953 and 971.
Mr Marlow will receive £20 for this contribution.
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This was first published in March 2009