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There's a matches riddle that I can't quite solve. Given the following layout (a 4 matches plus sign connected to a 8 matches square):

 __|__
 __|__
|     |
|__ __|

I need to transform this into exactly 3 squares by moving 5 matches only. It's driving me crazy, so if you know how to solve this, please share.

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1  
Do you mean the final result has to be exactly 3 squares, or does the final result only have to contain 3 squares? –  Zev Chonoles Oct 14 '11 at 0:41
    
@Zeb I meant exactly. I fixed the question to show this. –  Maayan Oct 14 '11 at 0:46
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1 Answer

up vote 5 down vote accepted
__|__
  |__ __
  |     |
  |__ __|
__|__
  |__ __
  |   __|
   __ __|
__|__
  |__ __
  |   __|
     |__|
__|__
  |__|__
      __|
     |__|
__
__|__
  |__|
      __|
     |__|
 __
|__|__
   |__|
       __
      |__|

Or do you mean?

   __|__
   __|__
  |     |
  |__ __|
   __|__
   __|__
  |__   |
  |   __|
   __|__
   __|__
  |__|  |
      __|
   __|__
   __|__|
  |__|  
      __|
   __
   __|__
   __|__|
  |__|  
        |
   __
  |__|__
   __|__|
  |__|  

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1  
it seems like there are 2 missing matches in your answer... And yes it should be exactly 5 moves. –  Maayan Oct 14 '11 at 0:51
    
I miss interpreted your post. I think this fixes it. –  Bill Cook Oct 14 '11 at 1:04
    
the second one is the correct one. Thanks! I was trying to solve this for a long time but kept missing this solution. Was this the result of trail and error, or did you come up with a way to systematically solve this? –  Maayan Oct 14 '11 at 1:44
1  
Realizing you can only move 5 sticks really limits which ones you can move. Like creating a new square from nothing would use up 4 moves! Also, you can't get exactly 3 squares if two of them share a side. Keeping these things in mind really limited what could be done. I'll leave both answers up. The other one is a nice puzzle too :) –  Bill Cook Oct 14 '11 at 1:55
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