Sudoku
Fill the grid so every row, column and box contains the digits one to nine exactly once.
Tap a cell, then a number.
How to use Sudoku
- 01Choose a difficulty and pick any empty cell.
- 02Enter a digit from one to nine, or switch to pencil mode to jot down candidates.
- 03Complete every row, column and three-by-three box using each digit exactly once.
About Sudoku
Every valid Sudoku has exactly one solution and can be reached by logic alone — guessing is never required. Start by scanning for digits that already appear several times on the board, since those constrain the remaining cells the most.
When simple scanning stalls, switch to candidate marks. A cell with only one possible digit, or a digit with only one possible cell in its box, is the backbone of almost every puzzle up to hard difficulty.
Frequently asked questions
- Does every puzzle have one solution?
- Yes, each generated puzzle is checked to have a single valid solution.
- Can I use pencil marks?
- Yes, switch to notes mode to write multiple candidates into a cell.
- Will it tell me when I make a mistake?
- Mistake checking is optional — turn it on to highlight conflicts as you type.
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