All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars    
perplexus dot info

Home > General
Prime clock (Posted on 2004-08-01) Difficulty: 3 of 5
Given a clock, rearrange six consecutive numbers on its face, so the sum of every pair of adjacent numbers is a prime.

See The Solution Submitted by Federico Kereki    
Rating: 3.7500 (8 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Solution trial & error solution | Comment 1 of 16

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
Please log in:
Login:
Password:
Remember me:
Sign up! | Forgot password


Search:
Search body:
Forums (0)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (12)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:
Copyright © 2002 - 2024 by Animus Pactum Consulting. All rights reserved. Privacy Information