Sudoku

Sudoku is a logic puzzle with 81 cells. Enter the numbers 1 to 9 so that each appears exactly once in every row, column and 3×3 box. The given numbers stay fixed. No arithmetic is needed.

Entering numbers

Select an empty cell, then tap a number below the grid. On a keyboard, you can also use the keys 1 to 9. Use the arrow keys to move between cells and Delete or Backspace to clear one of your entries.

Repeated numbers in a row, column or box are marked as conflicts. This helps you check the rules, but it is not a complete answer check: an incorrect number may initially create no visible conflict.

Using pencil notes

“Notes” switches to small candidate numbers. Use these to mark numbers that might fit an empty cell. Selecting the same candidate again removes it. Press N on the keyboard to toggle note mode.

When you enter a full-size number, the game removes that candidate from notes in the affected row, column and box. Still check your remaining notes regularly, especially after correcting an earlier entry.

Daily game and difficulty levels

The daily game uses Medium difficulty and gives everyone the same puzzle on the same day. Free play offers Easy, Medium and Hard. The generator removes givens only when exactly one solution remains. Difficulty depends on the reasoning required, not just the number of given cells.

Your numbers, notes and elapsed time are saved locally in this browser. No account is needed. Another browser does not inherit that progress, and clearing site data removes it. “Restart” resets the daily puzzle; in free play, it generates a new puzzle.

A useful first step

Look for a row, column or box with only a few gaps. List the missing numbers and eliminate those already present in intersecting regions. If only one candidate remains for a cell, you can enter it with confidence.

If you prefer sliding numbers, try 2048. In Minesweeper, numbers help you locate hidden mines. Find more puzzles under All games.