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Sunday Times Teaser 2611 – Simple Arithmetic

by Danny Roth

Published: 7 October 2012 (link)

George and Martha are teaching their great-grandchildren some simple arithmetic. “If you add two thirties to four tens you get a hundred,” George was saying, and he wrote it like this:

“Strangely,” added Martha, there are nine different letters there, and if you allow each letter to stand for a different digit, there is a unique sum which works.”

Which digit would be missing?


4 Comments Leave one →
  1. Brian Gladman permalink

    Here is my solution:

  2. geoffrounce permalink

    A different approach using permutations:

  3. Brian Gladman permalink

    Here is a further development of Geoff’s solution that is very fast on pypy:

  4. geoffrounce permalink

    As part of the joint effort, I think we should give some credit to Naim. I had seen him permute individual digits from letters to make larger numbers on Jim Randall’s Enigma site. I thought it was a method worth trying for this teaser.

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