Cryptarithm Game
Give different letters unique digits to make the written addition true.
Math puzzle challenges
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Help, keyboard and saved progress
Tap tiles or number boxes. Tab moves between fields and buttons; Enter in a field checks the current answer. Undo restores the most recent edit. Hints and Undo mark assistance.
Puzzle progress saves in your browser when available.
Daily puzzles switch at midnight UTC. Best scores are recorded separately for each difficulty.
How to Solve a Cryptarithm
Each letter represents one decimal digit from 0 to 9. A letter always means the same digit wherever it appears, and two different letters must never share a digit. The first letter of any number cannot represent zero. Find the digits so the displayed written addition is exactly correct.
Easy introduces a short addition pattern with a supplied digit. Normal uses a multi-column calculation and carries. Hard provides the classic five-digit result challenge with several interacting carry constraints. Enter one digit for each unknown letter, check your arithmetic, and adjust assignments until the full equation balances.
The checker converts the completed letter words into numbers, rejects repeated digits or illegal leading zeros, and verifies exact addition. Alternative assignments are accepted whenever they meet every rule, so the puzzle is judged mathematically rather than against a memorized answer key.
Column Addition and Carry Reasoning
For the simple pattern AB + BA = CC, the two addends equal 10A + B and 10B + A. Their sum is 11(A + B), while the result is 11C. The condition therefore simplifies to A + B = C, with different valid digits and no leading zero. For example, 23 + 32 = 55.
For a longer cryptarithm, begin at the ones column. Add its two digits and record the ones digit of the result. If that sum reaches 10, carry 1 into the tens column. Each following column is constrained by the incoming carry, its two letter digits and the outgoing carry. That turns a huge-looking guessing problem into several smaller arithmetic checks.
Take SEND + MORE = MONEY, a well-known example. One valid solution is 9567 + 1085 = 10652. The leading M must equal 1 because adding two four-digit numbers makes a five-digit result with a carry in the highest column. Working from such forced digits is more effective than random assignments.
Helpful Controls and Frequently Asked Questions
Tab through the letter fields on a keyboard, or use the numerical keyboard on a mobile phone. A hint supplies a digit from one valid solution and marks the puzzle assisted; if you have taken a different route, you may need to revise other entries. Undo restores the last changed field.
May different letters share a value? No. That breaks the one-to-one substitution. Can O be zero? Yes, if O is not the first letter of any displayed number. Can the same letter change value between the top and bottom of the sum? No. Consistency across every appearance is essential.
Each daily mode uses a repeatable puzzle for the UTC date and selected level. Practice mode lets you restart the calculation without losing the instructions. Your successful completion contributes to the site practice tracker, and unaided best scores are stored separately by difficulty.