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

Home > Just Math
26 out of 50 (Posted on 2016-11-25) Difficulty: 3 of 5
Prove the following statement:

In any set of 26 integers chosen from the set of (1,2,3, ...50) there must be at least a pair of numbers such that one of them divides the other.

Generalize.

No Solution Yet Submitted by Ady TZIDON    
Rating: 4.0000 (1 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Solution Inelegant proof? | Comment 5 of 10 |
We can pick at most one number from each of the following sets:
(1,2,4,8,16,32)
(3,27)
(5,25,50)
(6,12,24,48)
(7,49)
(9,18,36)
(10,20,40)
(11,22,44)
(13,26)
(14,28)
(15,30)
(17,34)
(19,38)
(21,42)
(23,46)
These 15 sets are mutually exclusive and contain 40 numbers, so 25 numbers are necessarily unused.  And, therefore we have proven that we cannot pick 26 numbers out of 50 such that no two divide each other.

However, this inelegant proof does permit generalization.

Edited on November 28, 2016, 5:11 pm
  Posted by Steve Herman on 2016-11-27 16:34:11

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


Search:
Search body:
Forums (1)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (15)
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