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Calcudoku
Calcuduku — also known as KenKen, Mathdoku, or Square Wisdom — was created by Japanese math teacher Tetsuya Miyamoto to sharpen mental arithmetic. It looks like Sudoku but replaces given digits with arithmetic "cages." Solving it trains both logic and calculation at once.
Calcudoku Rules
On an N×N grid, fill each row and each column with the numbers 1 through N exactly once — no repeats in any row or column. The grid has no separate boxes like Sudoku.
Heavily outlined groups of cells called cages each show a target number and an operation (+, −, ×, or ÷). The digits in a cage must produce that target when the operation is applied, in any order. Single-cell cages simply state their digit.
For subtraction and division cages, the result is taken between the cage's values regardless of order (larger minus smaller, larger divided by smaller). Unlike Killer Sudoku, a digit may repeat within a cage as long as it does not break the row or column rule. The finished grid is unique.
Calcudoku Strategy & Tips
Start with single-cell and small cages
A one-cell cage hands you a digit for free. Two-cell subtraction and division cages have only a handful of valid pairs, so solve those tight constraints before the big additive ones.
Factor multiplication cages
Break a product into the digit combinations available on your grid size. A cage of 12× on a 4-grid is {3,4} or {2,2,3}, immediately limiting what fits and where.
Apply the row-column total trick
Each row and column sums to a fixed total (for example 1+2+3+4+5+6 = 21 on a 6-grid). Use leftover sums to deduce cells when cages nearly cover a line.
Remember cages can repeat digits
Within a cage a number may appear twice if it lands in different rows and columns. Don't discard a combination just because it reuses a value — check the line rule instead.
Frequently Asked Questions
Is Calcudoku the same as KenKen?
Yes, they are the same puzzle. KenKen is the trademarked name created by Tetsuya Miyamoto; Calcudoku and Mathdoku are common alternative names.
Can numbers repeat in a Calcudoku cage?
Yes, a digit can repeat inside a cage as long as it does not appear twice in the same row or column. This is a key difference from Killer Sudoku, where cages never repeat.
How do subtraction cages work in Calcudoku?
The operation is applied without regard to order — you subtract the smaller value from the larger to hit the target, since there is no fixed sequence within a cage.
Does Calcudoku use 3×3 boxes like Sudoku?
No. Calcudoku has no inner boxes. Its only structural constraint beyond the cages is that each number appears once per row and once per column.