Kakuro
Kakuro is a number crossword. Black cells hold clues: the number below a cell's diagonal is the sum of the white run beneath it, the number above is the sum of the run to its right. Fill every white cell with a digit from 1 to 9 so each run adds up to its clue and no digit repeats within a run.
How to play
Every Kakuro here has exactly one solution and can be solved by logic alone. Its level is the hardest technique it needs, and the grid grows from 6×6 at Easy to 10×10 at Expert.
- Fill each white cell with a digit from 1 to 9.
- The digits of a run add up to the clue at its start: down sums below the diagonal, across sums above it.
- No digit repeats within a run.
Playing on this site
- Select a cell, then type a digit or tap it on the number pad. Arrow keys move the selection.
- Turn on Notes (or press N) to pencil in candidates instead of answers.
- Hint first points out any wrong digits, then names the next technique and shows where it applies before giving anything away.
- Your puzzle is saved in this browser, so you can come back to it later.
Techniques by level
Every technique the solver knows, from easiest to hardest. A puzzle's level is the hardest one it needs.
Easy
- Digit used
- This digit is already in the run, and a run never repeats a digit.
- Sum combinations
- Only a few sets of different digits add up to this clue with this many cells. Digits in none of them can go.
Medium
- Combinations that fit
- Some sets for this sum need a digit no cell of the run can still take. Only the sets that fit remain, and their digits.
- Hidden single
- Every set that makes this sum needs this digit, and only one cell of the run can take it.
- Locked digits
- These cells can only hold the same two or three digits between them, so the rest of the run cannot.
Hard
- Try the fillings
- No way of filling this run with different digits that adds up to its clue puts these digits in these cells.
Expert
- Contradiction
- This digit here breaks a sum a few steps later.
Questions
What are the most useful Kakuro sums to know?
Sums with only one set of digits: 3 in two cells is 1+2, 4 is 1+3, 16 is 7+9 and 17 is 8+9; in three cells, 6 is 1+2+3 and 24 is 7+8+9. Start where such runs cross.
Will I ever have to guess?
No. Every puzzle has exactly one solution that logic alone reaches, at every level.
Is Kakuro free to play here?
Yes. Every level is free, with no account and no sign-in.