This puzzle
- Difficulty
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- Cages
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- One-cell cages
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- Board
- 9×9
- Hardest step
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No digits are printed on a Killer Sudoku board. A cage of one cell states its own digit, so those are this game's givens — and the tier is decided by which techniques the solver actually needed, not by how many there are.
The rules
Fill the grid so every row, column and 3×3 box holds 1–9. Each dashed cage must add up to the small number in its corner, and no digit may repeat inside a cage.