What is KenKen?
KenKen (also known as Calcudoku or MathDoku) is a math logic puzzle invented by Japanese teacher Tetsuya Miyamoto. Like Sudoku, every row and column must contain each number exactly once. Unlike Sudoku, the grid is divided into heavily outlined groups of cells called cages, and each cage shows a target number with an arithmetic operation. The numbers you place inside a cage must produce the target using that operation.
How to play:
- Choose a grid size and how many puzzles you want to solve, then click Start Puzzle
- Tap or click a cell to select it, then tap a number button below the grid
- On desktop, you can also type numbers directly and move between cells with arrow keys
- Press Backspace, Delete, or the ✕ button to clear a cell
- The puzzle completes automatically the moment the grid is filled correctly
Reading the cages:
- 7+ means the cage's numbers add up to 7
- 2− means the difference between the two numbers is 2 (in either order)
- 6× means the cage's numbers multiply to 6
- 2÷ means one number divided by the other equals 2 (in either order)
- A cage with just a number and no operation is a single cell — enter that number directly
- Numbers may repeat inside a cage, as long as no row or column ever repeats a number
Solving tips:
- Start with single-cell cages — they are free numbers
- Look for cages with very few combinations: on a 4×4 grid, a 2-cell 3÷ cage can only be {1,3}, and a 12× cage can only be {3,4}
- Subtraction and division cages of extreme value are highly constraining — a 3− cage on a 4×4 grid must be {1,4}
- Cross-reference cage candidates with row and column eliminations, just like Sudoku scanning
- Every puzzle here is generated with exactly one solution
Scoring:
- Total Time: How long the full session took
- Avg per Puzzle: Total time divided by puzzles solved
- Hints Used: Each hint fills one correct cell — fewer is better