Alphametic Definition

A alphametic is a cryptarithmetic (number puzzle) where the letters used to represent distinct digits are derived from related words or meaningful phrases.

Examples

One of the most well known alphametics is "SEND MORE MONEY" first published by Henry Dudeney, a British puzzlist in 1924.

Rules

Alphametics have several rules as listed:

Identical digits are replaced by the same letter. Different digits are replaced by different letters.
After replacing all the letters with digits, the resulting arithmetic expression must be mathematically correct.
Numbers cannot start with 0. For example, the number 0900 is not valid.
Each problem must have exactly one solution, unless stated otherwise.
The problems will be in base 10 unless otherwise specified. This means that the letters replace some or all of the 10 digits. (0, 1, 2, 3, 4, 5, 6, 7, 8, 9)