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TWO + TWO = FOUR

cryptarithmdigitslogic

In the addition

  T W O
+ T W O
-------
F O U R

each letter stands for a different digit, and neither TWO nor FOUR begins with 0.

Find a solution, and determine how many different solutions there are.

Show a hint

FOUR is at most 2 × 999 = 1998, so F = 1. Then O is the last digit of 2 × O, which forces O to be even, and the hundreds column gives O from 2T or 2T + 1.

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