Calcudoku
Sudoku meets arithmetic: hit every cage's target.
About Calcudoku
Calcudoku mixes the row-and-column rule of Sudoku with simple arithmetic. Each cage is a small sum, difference, product or quotient to crack, and every puzzle here has exactly one solution.
How to play
Fill every row and column with the digits 1 to the grid size, each once. Each outlined cage shows a target and an operation (+ − × ÷): its digits must combine to that target. For − and ÷, start from the larger digit. Digits may repeat inside a cage if they're in different rows and columns.
Tips and strategies
- Start with single-cell cages: their target is the digit.
- A two-cell ÷ or − cage with a large target has very few digit pairs — list them.
- In each row the digits add up to the same total (10 for 4×4, 21 for 6×6); use it to finish cages.
Calcudoku strategy guide
Fill single-cell cages first, then list the possible combinations of small cages. On 6×6, a two-cell 11+ cage can only be 5 and 6, and a 5− cage can only be 1 and 6.
Multiplication cages are often the most restrictive: factor the target. A three-cell 60× cage on 6×6 can only be 3·4·5 or 2·5·6, so it must contain a 5.
Use the line totals. Every row and column adds up to 1 + 2 + … + n (21 on 6×6), so when cages fix all but one cell of a line, the last cell is the difference.
Frequently asked questions
How do I play Calcudoku?
Fill the grid so each row and column contains 1 to n once. The grid is split into cages; the digits in a cage must combine to its target using the cage's operation (+, −, × or ÷).
How do − and ÷ cages work?
They always have exactly two cells. Take the larger digit first: a 3− cage holds two digits that differ by 3, and a 2÷ cage holds two digits where one is twice the other. A single-cell cage simply shows its digit.
Can a digit repeat inside a cage?
Yes, as long as the repeats are not in the same row or column. Every puzzle — 4×4, 5×5, 6×6 or 7×7 — has exactly one solution.
Is Calcudoku free to play?
Yes. Every game on Puzzimo is completely free and runs in your browser on desktop, tablet and phone — no download or installation.
Do I need an account?
No. You can play instantly as a guest and still appear on the leaderboards. Sign in with Google, Discord or LINE to keep your scores on every device.
How does the daily Calcudoku challenge work?
Every day at 00:00 UTC everyone gets the same new puzzle. Only your first finish of the day counts on the leaderboard.
How are leaderboard results verified?
Our servers replay every move of your game and measure the time themselves, so leaderboard results can't be faked.