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Pandigital Squares (Posted on 2006-09-01) Difficulty: 3 of 5
Harry, Tom and I each found a four-digit perfect square and two three-digit perfect squares that among them used all the digits 0 - 9. No two solutions were identical. If I told you how many squares my solution had in common with each of the other two, you could deduce which squares formed my solution.

Which squares formed my solution?

Which square or squares (if any) did Harry's and Tom's solutions have in common?

  Submitted by Charlie    
Rating: 3.0000 (2 votes)
Solution: (Hide)
The only possible sets are:

 1089  324  576
 3025  169  784
 3025  196  784
 3025  784  961
 9025  361  784
 9801  324  576
If I had either of the two solutions that had 324 and 576 plus a unique four-digit square, you'd have no way of differentiating which I had. Likewise if I had any of the three solutions that shared 784 and 3025, along with a unique other three-digit number, you'd have no way of telling which of those sets I had.

What's left is that I must have had 9025, 361 and 784, of which I shared 784 with Harry and Tom

This checks out as the only possibility for sharing one number with each of the other two players.

Indeed Harry and Tom must be two of the players who shared 3025 and 784, as, if I had said I shared no numbers in common you would not have been able to deduce the original question, as either of the players with 324 and 576 would share none in common with any of the 784 players and vice versa.

So I had 9025, 361 and 784 and the other two shared 3025 and 784.

This is Enigma 1401 from New Scientist for July 22-28, 2006.

Comments: ( You must be logged in to post comments.)
  Subject Author Date
AnswerK Sengupta2009-01-01 16:07:41
re: Solutionvj2006-09-04 05:46:54
SolutionSolutionDej Mar2006-09-01 12:27:34
solutionvj2006-09-01 09:13:14
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