How to play Kakuro
A crossword with numbers: instead of words you write digits, and each run of cells has to add up to its clue.
The rules
- Every white cell gets a digit from 1 to 9.
- Each run adds up to its clue. The across clue sits top-right in the black cell, the down clue bottom-left.
- No digit repeats within a run.
- There is exactly one solution. You never have to guess.
Start with the unique sums
Some clues can only be made one way. Two cells adding to 3 are 1 and 2. Two cells adding to 17 are 8 and 9.
Look for those clues first. The order is still open, but the digits are already decided.
See every clue with a single combination
| Cells | Clue = digits |
|---|---|
| 2 | 3 = 1+24 = 1+316 = 7+917 = 8+9 |
| 3 | 6 = 1+2+37 = 1+2+423 = 6+8+924 = 7+8+9 |
| 4 | 10 = 1+2+3+411 = 1+2+3+529 = 5+7+8+930 = 6+7+8+9 |
| 5 | 15 = 1+2+3+4+516 = 1+2+3+4+634 = 4+6+7+8+935 = 5+6+7+8+9 |
| 6 | 21 = 1+2+3+4+5+622 = 1+2+3+4+5+738 = 3+5+6+7+8+939 = 4+5+6+7+8+9 |
| 7 | 28 = 1+2+3+4+5+6+729 = 1+2+3+4+5+6+841 = 2+4+5+6+7+8+942 = 3+4+5+6+7+8+9 |
| 8 | 36 = 1+2+3+4+5+6+7+837 = 1+2+3+4+5+6+7+938 = 1+2+3+4+5+6+8+939 = 1+2+3+4+5+7+8+940 = 1+2+3+4+6+7+8+941 = 1+2+3+5+6+7+8+942 = 1+2+4+5+6+7+8+943 = 1+3+4+5+6+7+8+944 = 2+3+4+5+6+7+8+9 |
Cross the clues
Where an across run meets a down run, the shared cell has to work for both.
Keep only the digits that appear in both clues. It works best where a short clue crosses a long one.
Think about the largest and smallest
Ask which digits cannot fit a run. Four cells adding to 26 cannot hold a 1: at most 1+9+8+7 = 25.
A digit that cannot fit a run cannot sit in the cell that crosses it either.
Subtract what is already placed
When part of a run is filled, what is left is a smaller puzzle. Three cells adding to 12 with a 9 placed leave 3 for two cells.
The line under the board does this subtraction for you. With Show combinations on, tap a clue to list its combinations.
When you are stuck
- Use notes to pencil in the digits a cell could still hold. A cell with a single note is solved.
- Pick a cell with two options and follow one. If it leads to a contradiction, it was the other.
- Hint fills the selected cell. Check marks any mistakes, and a full grid checks itself.
Controls
| 1…9 | Type the digit into the selected cell. Typing it again clears it. |
|---|---|
| ←↑↓→ | Move the selection. |
| ⌫0 | Clear the cell. |
| P | Toggle notes. |
| Z | Undo the last change. |