A cryptarithm (or alphametic) is a math puzzle where the digits in an arithmetic problem are replaced with letters. Each unique letter stands for a unique digit (0 through 9), and the leading letter of a number cannot be 0.

The World's Most Famous Puzzle:

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

How to Deduce the Solution Like a Detective

  1. Look at M in MONEY: When you add two 4-digit numbers, the maximum possible sum is 9,999 + 9,999 = 19,998. The carry into the fifth column can only ever be 1. Therefore, M = 1!
  2. Look at O: Since M = 1, in the thousands column S + 1 (+ possible carry) = 1O. S is at most 9, so 9 + 1 = 10. This means O = 0 and S = 9 (or 8 with carry)!

Following this logical chain reveals the full unique answer: 9,567 + 1,085 = 10,652. Cryptarithms teach rigorous logical thinking and deep place-value understanding.