Kakuro is a number crossword logic puzzle where every white cell receives one digit from 1 to 9. The black clue cells give totals for the across and down runs that start beside them, so the puzzle feels like a crossword built from arithmetic instead of words. A solved board must satisfy every clue sum and every no-repeat rule at the same time.

How do you play Kakuro online?

Select a white cell, enter a digit from 1 to 9, and keep checking the across and down clues that cross that cell. Each horizontal run must add to the clue on its left, each vertical run must add to the clue above it, and the same digit cannot appear twice inside one run. Online play makes that loop faster because you can undo, reset, use notes, and check conflicts without redrawing the grid.

What is a run in Kakuro?

A run is one uninterrupted group of white cells going across or down from a clue. For example, a two-cell run with a 17 clue can only use 8 and 9 in some order, while a three-cell run with a 6 clue can only use 1, 2, and 3. Thinking in runs is the key difference between Kakuro and normal arithmetic: the total matters, but the number of cells and the no-repeat rule matter just as much.

Can a Kakuro run repeat a number?

No. A single across or down run cannot repeat digits, even when the repeated digits would add to the clue. A 4 across two cells must be 1 and 3, not 2 and 2, and a 16 across two cells must be 7 and 9, not 8 and 8. The same digit can appear elsewhere on the board when it belongs to a different run.

Is Kakuro the same as Sudoku?

No. Both games use digits 1 through 9 and reward careful elimination, but the rule systems are different. Sudoku asks each row, column, and box to contain the digits without repetition. Kakuro asks each across or down run to hit a printed sum without repeating digits. A Sudoku habit of scanning whole rows is useful, but Kakuro usually starts with clue combinations and crossing runs.

What is the best way to start a Kakuro puzzle?

Start with the most restricted short sums, then use crossings to remove candidates. Two-cell sums such as 3, 4, 16, and 17 have very few legal pairs, so they are strong anchors. Write possible combinations before guessing, check whether a crossing run can accept each digit, and only place a number when both directions agree. A slower combination-first rhythm usually prevents more mistakes than blind arithmetic.

Kakuro Strategy: Sums, Runs, and No Repeats

A practical Kakuro strategy guide for combination thinking, run pressure, and contradiction checks.

Strong Kakuro solving is not raw arithmetic speed. It is the discipline of reducing combinations until each crossing cell has only one legal digit.

Think in combinations

A run has two constraints at once: the digits must add to the clue, and none may repeat. That means every clue has a finite set of possible combinations before you consider crossings.

Use crossing pressure

When an across run needs one of two pairs, inspect the down runs for each cell. A down clue can eliminate a digit even when the across sum still looks possible.

Use short contradiction checks

If logic stalls, test a candidate only until it creates a concrete failure such as a run with no possible sum. Long branches are a sign to return to combination marking.