Sudoku

What is Sudoku?

Sudoku is a classic logic-based number puzzle where players must fill a 9×9 grid with digits so that each column, each row, and each of the nine 3×3 subgrids contains all digits from 1 to 9.

The New York Times offers daily Sudoku puzzles at various difficulty levels.

Sudoku Rules

1. Grid: 9×9 grid divided into nine 3×3 boxes
2. Numbers: Use digits 1-9 only
3. Row Rule: Each row must contain 1-9 without repetition
4. Column Rule: Each column must contain 1-9 without repetition
5. Box Rule: Each 3×3 box must contain 1-9 without repetition
6. Given Numbers: Some numbers are pre-filled and cannot be changed

How To Play Sudoku

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Example Starting Grid

5 3 _ | _ 7 _ | _ _ _
6 _ _ | 1 9 5 | _ _ _
_ 9 8 | _ _ _ | _ 6 _
------+-------+------
8 _ _ | _ 6 _ | _ _ 3
4 _ _ | 8 _ 3 | _ _ 1
7 _ _ | _ 2 _ | _ _ 6
------+-------+------
_ 6 _ | _ _ _ | 2 8 _
_ _ _ | 4 1 9 | _ _ 5
_ _ _ | _ 8 _ | _ 7 9

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Solving Process

1. Look for Singles: Find cells where only one number can fit
2. Check Rows/Columns: Eliminate possibilities based on existing numbers
3. Box Analysis: Look at 3×3 boxes for constraints
4. Pencil Marks: Note possible numbers in empty cells
5. Iterate: Repeat until the grid is complete

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Sudoku Strategy Tips

Beginner Techniques

1. Naked Singles: A cell where only one number is possible
2. Hidden Singles: A number that can only go in one cell in a row/column/box
3. Scanning: Systematically check each number 1-9 to see where it can go

Intermediate Techniques

4. Naked Pairs: Two cells in a row/column/box that can only contain the same two numbers
5. Hidden Pairs: Two numbers that can only appear in two cells
6. Pointing Pairs: When a number in a box can only be in one row/column

Advanced Techniques

7. X-Wing: A pattern involving four cells that eliminates possibilities
8. Swordfish: Similar to X-Wing but with three rows/columns
9. Coloring: Using logic chains to eliminate possibilities

Difficulty Levels

Easy

• Many given numbers (35-40)
• Can be solved with basic techniques
• Good for beginners

Medium

• Moderate given numbers (30-35)
• Requires some intermediate techniques
• 15-30 minutes to solve

Hard

• Fewer given numbers (25-30)
• Requires advanced techniques
• 30-60 minutes to solve

Expert

• Very few given numbers (22-25)
• Requires complex logic chains
• 60+ minutes to solve

Common Mistakes to Avoid

1. Guessing: Sudoku should be solved with logic, not guessing
2. Missing Duplicates: Always check for repeated numbers
3. Ignoring Boxes: Don't forget the 3×3 box rule
4. Rushing: Take your time to avoid errors
5. Not Using Pencil Marks: Track possibilities in complex puzzles

Tips for Improvement

1. Start Easy: Build confidence with easier puzzles
2. Learn Techniques: Study solving strategies systematically
3. Practice Daily: Consistency improves pattern recognition
4. Use Pencil Marks: Note possibilities in difficult puzzles
5. Check Your Work: Verify rows, columns, and boxes regularly

Where To Play Sudoku?

Official game website:

👉 https://www.nytimes.com/puzzles/sudoku

New puzzles daily at multiple difficulty levels. NYT subscription provides access to all levels and archives.