Given a clock, rearrange six consecutive numbers on its face, so
the sum of every pair of adjacent numbers is a prime.
starting out we see that there are already 6 consecutive pairs of numbers that add up to prime numbers...
1 2 3 4 5 6 7 8 9 10 11 12 1
3 5 7 9 11 13 15 17 19 21 23 13
+ + + - + + - + + - + +
So the 6 numbers that we want to change are 5 - 10.
Through trial and error I found 2 solutions...
1 2 3 4 7 10 9 8 5 6 11 12
3 5 7 11 17 19 17 13 11 17 23
1 2 3 4 9 10 7 6 5 8 11 12
3 5 7 13 19 17 13 11 13 19 23
|
|
Posted by Danny
on 2004-08-01 10:41:13 |
trial & error solution
