Solution

(related to Problem: An Acrostic Puzzle)

There are twenty-six letters in the alphabet, giving $325$ different pairs. Every one of these pairs may be reversed, making $650$ ways. But every initial letter may be repeated as the final, producing $26$ other ways. The total is therefore $676$ different pairs. In other words, the answer is the square of the number of letters in the alphabet.


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References

Project Gutenberg

  1. Dudeney, H. E.: "Amusements in Mathematics", The Authors' Club, 1917

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