# Kakuro

Fill every white cell with a digit from 1 to 9 so that each across and down run adds up to the clue printed in the black cell before it.

- Category: Puzzle
- Features: Leaderboard
- Tags: puzzle, logic, grid, numbers, cross sums, cross-sums, brain, sums, addition, math

## How to play

### Goal

Fill every white cell with a digit from 1 to 9 so that each across and down run adds up to the clue printed in the black cell before it.

### Rules

• A clue is the small number in a black cell: the upper-right number is the sum of the run to its right, the lower-left number the sum of the run below it
• The digits in a single run must all be different
• There is no zero, and a run never repeats a digit — so a two-cell run that sums to 3 can only be 1 and 2

### How to Play

• Tap a white cell to select it, then tap a number — or press it on the keyboard — to place it
• Tap the same number again, or use Erase, to clear the cell
• A cell turns red only when it breaks a rule you can see: a repeated digit in a run, a run that overshoots its clue, or a full run that misses it — never because it disagrees with the hidden answer
• Pinch to zoom and drag to pan; Fit re-centres the board
• Hint reveals one cell
• Keyboard: arrows or WASD move the cursor, number keys place a value, Backspace clears, Z undoes

### Tips

• Start with short runs and extreme sums: a two-cell run of 3 is 1+2, a two-cell run of 17 is 8+9 — the only options
• Where an across run and a down run cross, the digit has to satisfy both sums at once
• Work out the possible digit sets for each run, then let the crossings rule them out

### Difficulty

Boards grow from a 5×5 grid up to 8×8, with more and shorter runs as the size rises. Larger boards lean harder on long chains of crossing sums.

Play Kakuro in the free Game Nest app for iPhone, iPad, and Android.