Given a clock, rearrange six consecutive numbers on its face, so the sum of every pair of adjacent numbers is a prime.

20,21,22,25,24,23 is one solution to the problem
Generally this permutaion a,a+1,a+2, a+5, a+ 4, a+3 will work whenever you have a prime quadruple
30n+11, 30n+13, 30n+17, 30n + 19 and we let a = 30n+10

Posted by neshal on 2004-08-02 05:25:23