Posted by **Jane** on Wednesday, February 3, 2010 at 1:57pm.

Andrew arranged the number 1, 2, 3, ...11, 12 into six pairs so that the sum ofany two numbers in a pair is prime and no two of these primes are equal. find the primes and the pairs

- Maths -
**drwls**, Wednesday, February 3, 2010 at 2:53pm
I had to solve this by "trial and error" and finally came up with this. There many be other solutions.

1 + 4 = 5

2 + 5 = 7

3 + 8 = 11

6 + 7 = 13

9 + 10 = 19

11 + 12 = 23

Other prime-number-sum combinations possible would have been 3 and 17, but by forming them I had to use numbers twice or get duplicate sums.

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