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#1 Help Me ! » nn x nnn = nnnn » 2013-09-17 23:15:01

Oakbank1953
Replies: 1

Years ago, somehow, I stumbled across a problem.  Using only the digits 1-9 (not zero, and no duplications) how many combinations of nn x nnn = nnnn.  You can see that it is a 2 digit number multiplied by a three digit number = a four digit number, using only the 9 digits.  I have no idea what this problem was called (I presume it has a name...?) and I can`t find a reference to it.  Have you heard of this one?  I ended up writing a computer program to generate all the combinations and tell me the answer.  Yes it`s a cheat, but there are a lot of possible combinations...:)  Not many valid answers, though.  Peter

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