Verbal arithmetic
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Verbal arithmetic, also known as cryptarithmetic, is a type of mathematical game in which letters represent numbers. Often the letters are arranged in such a fashion that they also form words, a device that has been called an "alphametic". The arrangement of the letters may involve any of the basic operations of arithmetic. An example involving addition, created by Henry Dudeney, is:

  S E N D
  M O R E
M O N E Y

In this puzzle, O=0, M=1, Y=2, E=5, N=6, D=7, R=8, and S=9. A verbal arithmetic puzzle should adhere to the conventions of arithmetic notation, with each letter representing a different number, and the puzzle should only have one solution.

The original article can be found at: http://en.wikipedia.org/wiki/Verbal_arithmetic.
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