14
27
35
45
53
64
76
85
94
↶ Undo
⌫ Erase
✎ Notes
💡 Hint
How to play Sudoku
Fill every row, every column and every 3×3 box with the digits 1 to 9, each once. Pick a square, then a digit on the pad (or press 1–9). Turn on Notes (N) to pencil in the digits a square might hold; placing a digit clears it from the notes it can see. A digit repeated in a row, column or box turns red. Erase with Backspace, move with the arrow keys, and undo with Ctrl+Z. Stuck? A hint fills in the selected square, or puts right a wrong one, but only a solve without hints sets a best time. Your game is saved as you play.
Levels
- Easy: about 38 clues, and every step can be found with singles alone.
- Medium: about 30 clues. Still solvable with singles, but they are harder to spot.
- Hard: about 26 clues, needing more than singles, such as pairs or pointing digits.
- Expert: as few clues as possible while keeping a single solution.
Solving techniques
- Naked single: a square where only one digit is still possible, because the other eight already appear in its row, column or box.
- Hidden single: a digit that can go in only one square of a row, column or box, even if that square could hold other digits.
- Scan one digit at a time across each band of three boxes. It is the quickest way to find hidden singles.
- Naked pair: two squares in a unit that can only hold the same two digits. Those digits can be removed from the notes of every other square in that unit.
- Pointing: if a digit's only places in a box all lie in one row or column, it can't go anywhere else in that row or column outside the box.
- No guessing needed. Every puzzle has exactly one solution and can be solved by logic alone.