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Sudoku where dotted cages must add up to their target sum.
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How to play Killer Sudoku (Sum Sudoku)
Killer Sudoku, also called sum Sudoku, combines Sudoku with arithmetic. The grid is divided into dotted cages, each showing a small target number. The digits in a cage must add up to that target and never repeat — on top of the normal Sudoku rules.
- 1Follow Sudoku rules. Every row, column and 3×3 box must contain 1–9 with no repeats.
- 2Make each cage sum correct. The digits inside each dotted cage must add up to the small number shown in its corner.
- 3Never repeat inside a cage. A digit can't appear twice within the same cage, even if the sum would still work.
- 4Use the rule of 45. Each row, column and box totals 45. Compare that to the cage sums crossing it to deduce missing digits.
- 5Pencil in cage combinations. Use Notes to track which digit combinations can make each cage's sum, then eliminate as you solve.
Tips & strategy
Hunt for cages with few combinations: a 2-cell cage summing to 3 must be {1,2}; a 3-cell cage summing to 6 must be {1,2,3}. These 'locked' cages give you certain digits to anchor the rest of the grid. The rule of 45 across a box with one cage poking out is the classic next step.
Frequently asked questions
What is Killer Sudoku?
Killer Sudoku is Sudoku with cages: the grid is split into dotted groups, each with a target sum. The digits in a cage must add to that sum without repeating, in addition to the usual row, column and box rules.
Can a digit repeat in a Killer Sudoku cage?
No. Digits must be unique within a cage, just as they're unique within a row, column or box.
What is the rule of 45 in Killer Sudoku?
Every row, column and 3×3 box contains 1–9, which always sums to 45. Comparing 45 to the cage sums that cross a region lets you deduce the value of leftover cells.
Is Killer Sudoku harder than normal Sudoku?
It adds arithmetic, so it feels more challenging, but the cage sums also give extra clues. Start on Easy and work up.
Is Killer Sudoku free?
Yes — free in your browser, play instantly. Solve fast for a speed bonus and climb the live leaderboard.
Where can I play Killer Sudoku online for free?
You can play Killer Sudoku free right here on PuzzlePage, in any browser with no download. You get a fresh daily puzzle, several difficulty levels, a solving timer, a notes mode for pencilling in cage combinations, and a live leaderboard — on both desktop and mobile.
Which site has the best Killer Sudoku puzzles?
The best Killer Sudoku sites give you new puzzles daily, multiple difficulty levels, and cage sums with exactly one valid solution. Helpful extras are a notes mode for cage combinations, mistake checking, a timer, and instant play. PuzzlePage includes all of these for free.
Is there a new Killer Sudoku puzzle every day?
Yes. PuzzlePage publishes a new Killer Sudoku every day, so there is always a fresh sum-cage grid to solve, and the live leaderboard lets you compare your solve time with other players.
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