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        riddles >> easy >> Pigeonholing a grid
        
(Message started by: ecoist on Jun 16^th, 2007, 9:00pm)

Title: Pigeonholing a grid
Post by ecoist on Jun 16^th, 2007, 9:00pm

Four matchsticks make the sides of a square. 40 matchsticks make a 4x4 grid of 16 such squares. Show that, given any 13 of these matchsticks, at least two of them touch each other.

Title: Re: Pigeonholing a grid
Post by Aryabhatta on Jun 16^th, 2007, 9:54pm

[hide] 26 pigeons, 25 holes [/hide]