Calcudoku Game — Play Free Online, 6 Grid Sizes, 4 Operator Modes

How to play Calcudoku

Fill an N×N grid with 1 to N — no repeats in a row or column — so every cage hits its target using its operation.

An N×N grid uses the digits 1 to N. Each row and each column contains each digit exactly once.
Bold outlines group the cells into cages. Each cage shows a target and an operation: + − × or ÷.
The digits in a cage must make the target with that operation. For − and ÷ the cage has two cells, and you take the larger number first (6 − 2 = 4, 6 ÷ 2 = 3).
A one-cell cage simply gives you the digit.
A digit may repeat inside a cage, as long as the copies are not in the same row or column (possible only in L-shaped or larger cages).

Choose a grid size and a difficulty, then press Generate Puzzle.
Click a cell and type a digit, or use the on-screen keypad. Notes switches to pencil marks.
Undo steps back; Force places one digit that has only one possible value; Check marks mistakes in red without giving away the answer.
Operators Hidden mode hides the operation in every cage — the hardest way to play.
Stuck? Send to Solver opens the same puzzle in the step-by-step solver. Send to Slate opens it as a board on the Slate whiteboard, to solve in front of a class.

Fill the freebies. One-cell cages are given digits. Write them in first.
List the few options. A two-cell 3− cage in a 4×4 can only be 1 and 4. A 2÷ cage is 1&2, 2&4 or 3&6 depending on the grid size.
Use large products. Multiplication cages with big targets have few factorisations — 60× in three cells of a 5×5 must be 3, 4 and 5.
Row and column totals. Every row adds up to 1+2+…+N. On a 6×6 that is 21, so cages that share a row tell you about the leftover cells.

The full guide, with a worked example and common mistakes: How to play Calcudoku.

Are Calcudoku, Mathdoku and KenDoku the same puzzle?

Yes — the same rules under different names. This site has a cage calculator under each name: Calcudoku, Mathdoku and KenDoku.

Which number comes first in a − or ÷ cage?

The larger. A 2÷ cage of 3 and 6 means 6 ÷ 3.

Can digits repeat inside a cage?

Only when the cage is bent so the repeated digits sit in different rows and different columns.

What is Operators Hidden mode?

A harder mode in the Calcudoku game where cages show only the target — you deduce the operation as well as the digits.

How do I see every combination for a cage?

Enter the grid size, operation, cells and target in the cage calculator, or browse the cage combinations tables.