Cut the knot: learn to enjoy mathematics
A math books store at a unique math study site. Learn to enjoy mathematics.
Terms of use
Privacy Policy

More Mathematics
CTK Exchange

Games to Relax
Guest book
Recommend this site

Sites for teachers
Sites for parents

Manifesto: what CTK is about Buying a book is a commitment to learning Things you can find on CTK Email to Cut The Knot Recommend this page

Pennies in Boxes

Here is a problem:

Suppose N pennies are randomly distributed into several boxes. Take any two boxes A and B with p and q pennies, respectively. If p ≥ q you are allowed to remove q pennies from box A and put them into box B, and this action is called an operation. Show that regardless of the original distribution of pennies, a finite number of such operations can move all the pennies into one or two boxes. If N = 2n, pennies can be moved into a single box.

(To perform an operation in the applet below click on two boxes - circles - in succession.)

<hr> <h3> This applet requires Sun's Java VM 2 which your browser may perceive as a popup. Which it is not. If you want to see the applet work, visit Sun's website at, download and install Java VM and enjoy the applet. </h3> <hr>


Copyright © 1996-2008 Alexander Bogomolny