Sudoku
Classic Sudoku puzzle. Fill the grid so that every row, column, and 3×3 box contains the digits 1 through 9. Enter a seed for a specific puzzle, or leave blank for a random one.
FAQ
Sudoku is a logic puzzle where you fill a 9x9 grid so that every row, column, and 3x3 box contains the digits 1-9 exactly once. It requires no math — only logical deduction.
Start with scanning — check each row, column, and box for digits that can only go in one place. Use pencil marks to track possibilities. Advanced techniques include hidden pairs, X-wings, and swordfish.
Yes. Difficulty depends on how many cells are pre-filled and which solving techniques are required. Easy puzzles need only basic scanning, while hard puzzles require advanced deduction techniques.
About this test
Sudoku is the world's most popular number puzzle. Fill the grid using logic alone — no math required, just pure deductive reasoning.
How It Works
Fill every empty cell with a digit 1-9 so that each row, column, and 3x3 box contains each digit exactly once. The puzzle has one unique solution.
History
Modern Sudoku was designed by Howard Garns in 1979 (as "Number Place") and became a worldwide phenomenon when popularized by Japanese publisher Nikoli in 1986. The name means "single number" in Japanese.
Solving Tips
- Start with rows, columns, or boxes that have the most filled cells
- Use pencil marks to track possible values for each cell
- Look for naked singles (cells with only one possibility)
- Scan for hidden singles (digits that can only go in one place in a row/column/box)