Kakuro
Puzzle · 7 playsKakuro
A crossword built from sums — fill every run with digits that add up exactly.
About Kakuro
Often described as the mathematical cousin of the crossword. Every run of white cells carries a target total printed in the black clue cell beside it, and you fill that run with digits from 1 to 9 so they add up precisely — with no digit repeated inside the same run. The arithmetic stays simple; the pleasure lives in the combinations, where a run of four cells totalling 10 can only ever be one set of digits. Every puzzle is solvable by deduction alone. Free to play in your browser — no download, no sign-up.
How to Play
Each clue number is the total of the run of white cells to its right or below it. Fill runs with digits 1–9 — no digit may repeat inside a single run. Runs cross one another, so every cell has to satisfy both its across total and its down total.
Tips & Strategy
Learn the unique combinations and half the puzzle solves itself. Some totals can be made in exactly one way: 3-in-two is 1+2, 4-in-two is 1+3, 16-in-two is 7+9, 17-in-two is 8+9. In three cells, 6 is 1+2+3, 7 is 1+2+4, 23 is 6+8+9 and 24 is 7+8+9. In four cells, 10 is 1+2+3+4 and 30 is 6+7+8+9. Pencil those sets in the moment you see them — you don't know the order yet, but you know the digits.
Work the intersections, never a single run in isolation. The real deductions come where a constrained across-run crosses a constrained down-run: if the across cell can only be {8,9} and the down cell can only be {1,2,3}, the crossing is impossible and one of your assumptions is wrong. Where the two candidate sets overlap in exactly one digit, you have a placement.
Use the 45-rule on blocks of runs. A full nine-cell line holds 1 through 9, so it totals 45. If a region is almost enclosed by runs whose clues you know, the sum of those clues minus 45 tells you what a single stray cell must be. This is the technique that cracks the big boards.
When a run is nearly complete, stop thinking in combinations and just subtract. A 5-cell run totalling 28 with 6, 9 and 3 already placed needs two digits summing to 10 from what remains — often a single legal pair. And remember the negative information: a digit already used elsewhere in a crossing run is excluded here too, and eliminating candidates is usually faster than hunting for the answer directly.