Cryptarithms are also called Alphametics, Verbal Arithmetic or Letter Arithmetic - they are puzzles where an arithmetic sum has had its digits replaced by letters of the alphabet. The idea of the puzzle is to restore the original sum. Although many people think they were invented by the famous puzzlist Sam Loyd, an example published in 1864, when Loyd was only 23, disproves this idea. They were given the name **crypt-arithmetic** in 1931, and the name **alphametic** in 1955.

Solving cryptarithms is done by clever deductions of what certain letters represent, and at times considering all possibilities for other letters. The idea that letters can represent numbers means that cryptarithms are not just interesting and challenging math puzzles - they can also help introduce schoolkids to algebra.

I got the idea for this site after writing a computer program to find cryptarithms. I wrote the computer program so I could add a page about cryptarithms to Dr Mike's Math Games for Kids, a website I've made with about a hundred free math games, puzzles and other resources for elementary school kids - and their parents and teachers.

When the program started producing literally millions of cryptarithms, I decided to put them all onto a CD. Now, I've decided to put the CD online right here!

The rules for cryptarithm puzzles are simple. Each letter represents one of the digits 0 to 9. Different letters represent different digits. The first digit in a number can't be 0. Your job is to find out what digit each letter represents. Cryptarithms date back at least 140 years, if not much more!