How to Play Kakuro — Beginner Guide to Number Crossword

Kakuro looks like a crossword puzzle with a math problem inside it. Black cells contain clue numbers, white cells are empty squares you fill with digits 1–9. The goal: fill every white cell so that each "run" (a consecutive sequence of white cells) adds up to its clue.

The three rules

Kakuro has exactly three rules:

1. Fill every white cell with a digit from 1 to 9.
2. The digits in each horizontal run must sum to the clue on its left. The digits in each vertical run must sum to the clue above.
3. No digit may appear more than once within a single run.

That is the complete ruleset. Every Kakuro puzzle follows only these three constraints.

Reading the clues

Each black cell can contain two clues: a number in the upper-right portion (for the run going right, the "across" clue) and a number in the lower-left portion (for the run going down). The diagonal line divides these two values.

Your first moves

Start with the shortest runs and the most extreme sums. A 2-cell run summing to 3 must contain 1 and 2 — there is no other possibility. A 2-cell run summing to 17 must contain 8 and 9. These forced combinations give you an immediate foothold.

Working from intersections

Every white cell belongs to exactly two runs — one across and one down. When you can narrow the candidates for both runs intersecting at a cell, you can often determine the exact digit. This intersection logic is what makes Kakuro feel like a logical web rather than trial-and-error.

How Kakuro differs from Sudoku

In Sudoku, every digit 1–9 appears exactly once per row, column, and box. In Kakuro, there is no such global constraint. Digits can repeat across different runs in the same row or column — they just cannot repeat within a single run. This makes Kakuro a different kind of deduction.