🔟 Sudoku
While often associated with Japan, Sudoku was invented by American architect Howard Garns in 1979 under the name 'Number Place.' It was popularized in Japan by Nikoli in 1986, who named it Sudoku ('single number'). The global craze began in 2004 when The Times of London started publishing daily puzzles.
How to Play Sudoku
🖥️ Desktop
Click an empty cell to select it, then click a number button (1-9) to fill it in. Each row, column, and 3×3 box must contain all digits 1-9 with no repeats. Pre-filled numbers cannot be changed. Use ✕ to clear a cell.
📱 Mobile
Tap an empty cell to select it, then tap a number to place it. Same rules — no repeated digits in any row, column, or 3×3 box. Tap ✕ to erase.
Game Features
- ✓Classic 9×9 Sudoku grid
- ✓Pre-filled puzzle with unique solution
- ✓Click-to-fill number input
- ✓Clear button for corrections
- ✓Visual highlighting of selected cell
Tips & Tricks
- Start with rows or boxes that have the most pre-filled numbers
- Look for 'naked singles' — cells where only one number is possible
- Scan each number 1-9 across the whole board to find where it must go
- Focus on 3×3 boxes when stuck
- Use elimination — cross out impossible numbers mentally
Frequently Asked Questions
Does Sudoku require math?
No! Sudoku is purely a logic puzzle. You could replace digits with any nine distinct symbols and it would work identically. No arithmetic is involved.
How many valid Sudoku puzzles exist?
There are approximately 6.67 sextillion valid completed Sudoku grids. Accounting for symmetries, there are about 5.47 billion essentially different grids.
What makes a good Sudoku puzzle?
A well-designed Sudoku has exactly one solution and can be solved through logic alone without guessing. Difficulty depends on which techniques are required, not just how many cells are pre-filled.