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

Home > Logic
Magic Rods (Posted on 2003-11-11) Difficulty: 4 of 5
You need to make a set of five rods for a magic trick, with numbers on them ranging from 1 to 31 inclusive. Then you ask people to pick a number and show you only the top number of whatever rods it is on. From that you have to guess which number the person picked. This has to be done within a few seconds and isn't a matter of remembering what numbers are on them.

What numbers should be on each of the five rods?

See The Solution Submitted by Lewis    
Rating: 4.0000 (7 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Solution solution | Comment 7 of 13 |
Ah yes, that old binary system trick...

Think of the binary system. All the numbers ending in 1 in the binary system go on the first rod. All the numbers with a 1 in the 10's digit go on the second rod. Then all those with a 1 in the 100's digit on the third, and so on. The top numbers should be 1,2,4,8, and 16. Then, simply add the numbers to get the number the person thought of.

I'm probably repeating something, but I hope I brought in at least one new idea.
  Posted by Tristan on 2003-11-11 18:59:48
Please log in:
Login:
Password:
Remember me:
Sign up! | Forgot password


Search:
Search body:
Forums (5)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (1)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:
Copyright © 2002 - 2020 by Animus Pactum Consulting. All rights reserved. Privacy Information