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Inverting Triangles (Posted on 2005-08-15) Difficulty: 1 of 5
A piece of paper had the following diagram:
               o              o o o o
      From:   o o         To:  o o o
             o o o              o o
            o o o o              o
Below it, it read "Given the initial formation of ten coins, move exactly # coins to produce the end formation." It was pretty obvious that # stood for a digit, but it was smudged and couldn't be read. What possible numbers could it have been so the problem was solvable?

To allow explaining the solution, number the coins like this:

           0 
          1 2
         3 4 5
        6 7 8 9
Note: This problem was inspired by a forum question by Nicole.

No Solution Yet Submitted by Erik O.    
Rating: 2.1667 (6 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
re(3): 7 ways - your rules | Comment 8 of 14 |
(In reply to re(2): 7 ways - your rules by owl)

I have no quarrel with Lisa's solutions, just wondering what her thoughts were, and what rules she gave herself to work with.

Erik O. certainly opened up a forum for conjecture which has been valuable to explore.

  Posted by brianjn on 2005-08-16 01:42:35

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