**From New Scientist #1431, 22nd November 1984** [link]

The latest addition sum which Uncle Bungle has just made up was, of course, rather a long one. But in my opinion this was no excuse for his producing it proudly (yes, proudly), for his friends to see the mistake that he had made. What is meant to happen in these addition sums is for the same letter to stand for the same digit wherever it appears, and for different letters to stand for different digits. And so they do in this puzzle except for Uncle Bungle’s one silly mistake.

The sum looks like this:

Which letter was wrong, and what should it be?

Write out the correct addition sum.

[enigma284]

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This Python program uses the [[

`SubstitutedSum()`

]] solver from theenigma.pylibrary. It runs in 748ms.Solution:The final letter (units digit) in the result is wrong – it should be an L not an A. The correct addition sum then reads 2796085926 + 2794632926 = 5590718852.