Bowling Pin Problem

Date: 02/17/2006 at 11:33:24
From: Andrea
Subject: (no subject)

Ten bowling pins are set up in the usual way forming a triangle with 
the point facing the bowler.  How can 3 pins be moved so that the 10 
pins are still set up in the conventional manner but with the point 
of the triangle pointing straight away from the bowler?

My friend and I have been working on this problem for two days 
straight without any progress.  We were wondering if it is even 
possible to get an answer.  We have tried many different ways of
finding an answer, and every time we can only get it to where you move
4 pins not 3.

Date: 02/17/2006 at 12:38:56
From: Doctor Ian
Subject: Re: 

Hi Andrea,

I'll give you a hint.  If the original triangle is below, 

        0
      1   2
    3   4   5
  6   7   8   9
        
the pins you need to move are 0, 6, and 9.  

Let me know if this helps. 

- Doctor Ian, The Math Forum
  http://mathforum.org/dr.math/