Sudoku
Fill every row, column, and box with the numbers 1 to 9.
Why you will love it
About Sudoku
Sudoku is a logic-based number puzzle that challenges players to fill a 9×9 grid with digits 1-9. Each row, column, and 3×3 box must contain all digits exactly once. This Japanese puzzle game has become one of the world's most popular brain training activities.
Learn Sudoku in a minute
Sudoku is the classic logic puzzle where you fill a 9x9 grid so every row, column, and 3x3 box holds the digits 1 to 9 exactly once. No maths required, just clear thinking, and here it is completely free and ad-free, right in your browser.
Sudoku rules
Sudoku is played on a single 9x9 grid split into nine boxes. A handful of rules govern every move, from where a digit can go to what it takes to solve the puzzle.
- Row Rule: Each row must contain digits 1-9 with no repetition
- Column Rule: Each column must contain digits 1-9 with no repetition
- Box Rule: Each 3×3 box must contain digits 1-9 with no repetition
- Fixed Clues: Given numbers (clues) cannot be changed
- Unique Solution: Only one solution exists for each puzzle
- Logic Only: No guessing required - every move can be logically deduced
Solving techniques and strategies
A few reliable techniques dramatically speed up your solving. Start with the basics, then layer in the advanced tactics once they feel natural.
Beginner Techniques:
- Naked Singles: Find cells where only one number can fit. This is the most basic step.
- Hidden Singles: Find numbers that can only go in one cell within a row, column, or box. Look for a number that appears frequently.
- Scanning: Systematically check each row, column, and box for missing numbers. Cross-hatching is a great way to do this.
Advanced Techniques:
- Naked Pairs: Two cells in the same unit that can only contain the same two numbers. This eliminates those numbers from other cells in that unit.
- Pointing Pairs: When a number in a box points to a specific row or column, you can eliminate it from the rest of that row or column.
- Box/Line Reduction: Eliminate possibilities based on box and line interactions. This requires careful observation.
- X-Wing: Advanced pattern recognition for eliminating candidates. Useful for hard puzzles.
Difficulty levels
Every level uses the same rules, but the number of starting clues sets how hard you have to think to reach the solution.
- Easy: More given numbers, solvable with basic techniques
- Medium: Fewer clues, requires intermediate logical deduction
- Hard: Minimal clues, demands advanced solving techniques and patience
Benefits of playing Sudoku
Sudoku is more than a way to pass time. A quick puzzle sharpens focus, exercises logic, and gives your mind a calm reset.
- Logical Thinking: Develops systematic problem-solving approach
- Pattern Recognition: Improves ability to spot number patterns and relationships
- Concentration: Enhances focus and sustained attention
- Memory Training: Exercises working memory and recall abilities
- Stress Relief: Provides meditative focus and mental relaxation
- Brain Health: Regular play may help maintain cognitive function
Frequently asked questions
Quick answers to the things players ask most about Sudoku.
Is Sudoku a math game?
No, Sudoku is purely a logic puzzle. Despite using numbers, no arithmetic is involved. The numbers could be replaced with letters or symbols - it's about logical deduction and pattern recognition.
How long does it take to solve a Sudoku puzzle?
Solving time varies greatly: Easy puzzles may take 10-20 minutes for beginners, Medium puzzles 20-45 minutes, and Hard puzzles can take 45+ minutes even for experienced players.
What if I get stuck on a puzzle?
Try the Hint button for a helpful nudge, use the Check button to verify your current solution, or take a break and return with fresh eyes. Sometimes stepping away helps you see new possibilities.
Where did Sudoku originate?
While popularized in Japan (where "Sudoku" means "single digit"), the puzzle concept originated from Latin Squares studied by mathematician Leonhard Euler in the 18th century. Modern Sudoku was developed in 1979 by Howard Garns in the United States.
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