What do you get if you the numbers 1 to 12 into six pairs so that the sum of each pair is a prime number and all prime numbers are different?

1+2...+12=78

6 Prime number combinations that make 78.

Constraints: x>=3 x<=23 x=/=x

3+7+11+17+19+21=78

Test:

1+2=3

3+4=7

5+6=11

7+10=17

11+8=19

9+12=21

You get: 3, 7, 11, 17, 19, and 21.