Sudoku
Fill the grid — no repeats
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About Sudoku
Sudoku is the timeless number-placement puzzle. Fill the 9x9 grid so every row, column, and 3x3 box contains each digit from 1 to 9 exactly once. Easy, medium, and hard puzzles — generated fresh every time. Free to play online.
How to play Sudoku
- Fill the 9×9 grid so every row, column, and 3×3 box contains the digits 1–9 exactly once.
- Click (or tap) a cell, then type a number or use the on-screen pad.
- Conflicting cells are highlighted in red. Use that to spot mistakes early.
Solving techniques
Start with the easy wins: scan rows, columns, and boxes for cells that have only one possible number ("naked singles"). After those are gone, look for "hidden singles" — a number that can only go in one cell of a given row, column, or box even if that cell has other candidates. Harder puzzles need pencil-marks; this version highlights conflicts to make manual marking less necessary.