Talk:Verbal arithmetic

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[edit] Which Vatriquant?

Some web pages (including a couple of French ones) give "Maurice Vatriquant" or "M. Vatriquant" as the true name of Minos, the coiner of the name "crypt-arithmetique". However Don Knuth and David Singmaster give "S. Vatriquant". Who is right? Both?
Jorge Stolfi 06:50, 24 May 2004 (UTC)

[edit] Usefulness of casting out nines

I don't see the usefulness of casting out nines for solving alphametics, at least 2-addend ones. For example, in SEND + MORE = MONEY, M, O, S and R are solved in short order. The casting out nines rule then gives you E + D - Y + 1 = 0 mod 9. But this constraint doesn't give you anything that the right-most column doesn't. In general, casting out nines gives you equations with too many variables. Other techniques are much more helpful:

  • mod 10 arithmetic
  • treating columns as simultaneous equations
  • carry analysis
  • parity

Unless other types of alphametic puzzles get more mileage out of casting out nines, I'm inclined to remove its mention as an effective technique, and point the reader at techniques that work a little better.
JamesMayfield 19:33, 3 November 2006 (UTC)

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