GET TO KNOW THE GAME
How to play Sudoku
Sudoku is a number placement puzzle on a 9 × 9 grid. Fill each empty cell so that every row, column and 3 × 3 box contains the digits 1 through 9 exactly once. The starting clues stay fixed, and each puzzle has one solution.
The rules
- Select an empty cell and review its row, column and 3 × 3 box.
- Enter a digit that satisfies all three areas. Use Notes to record possible digits while you work.
- Fill every editable cell correctly to complete the puzzle. Use Check when you want feedback on your current entries.
Controls
Select a cell, then use the number pad or press 1–9 while the board is focused. Erase, Backspace, or Delete clears an editable cell. Notes adds or removes small candidate numbers. Check highlights incorrect entries without supplying the answer.
How scoring works
Complete the grid to record your active time in seconds. The timer pauses when you pause or hide the tab. Lower times are better; Easy and Standard personal bests are stored separately.
Tips for your next round
- Start with a row, column or box that is nearly full, then check its missing digits against the intersecting areas.
- A digit may have several candidates in a row but only one possible place within a box. Look for both kinds of single position.
- Your unfinished round is saved in this browser. Return to the same game, mode, and difficulty to continue. A daily challenge uses the UTC date; clearing browser data removes saved rounds.
Is Sudoku a math game?
Sudoku uses digits as nine distinct symbols. You do not add or multiply them; you work out which positions satisfy the row, column and box rules.
Can a puzzle have several valid answers?
The puzzles in this version are checked for a single solution. Notes are only reminders for your reasoning and do not count as filled answers.