Sudoku Solving Techniques
Master these essential strategies to solve any Sudoku puzzle by hand. From beginner basics to advanced techniques.
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Beginner Techniques (Easy)
1. Naked Singles (Solo Numbers)
The most basic technique. When a cell can only contain one possible number, that's a naked single. Look for cells where all other numbers (1-9) are already present in the same row, column, or 3×3 box.
How to find:
- • Scan each empty cell
- • Check what numbers are missing in its row, column, and box
- • If only one number is possible, fill it in
Only 2 can fit here
Intermediate Techniques (Medium-Hard)
3. Naked Pairs
When two cells in the same row, column, or box can only contain the same two numbers, those numbers can be eliminated from all other cells in that unit.
Example: If cells A and B can only be 3 or 7, then no other cells in their row/column/box can be 3 or 7.
4. Pointing Pairs (Box-Line Reduction)
When a number appears in only one row or column within a 3×3 box, it can be eliminated from the same row or column in other boxes.
Logic: If number 8 can only appear in the top row of a box, then 8 cannot appear anywhere else in that row.
6. Naked Triples
Similar to naked pairs, but with three cells that can only contain the same three numbers. These three numbers can be eliminated from all other cells in that unit.
Example: If cells A, B, and C can only contain 2, 5, and 8, then no other cells in their row/column/box can contain 2, 5, or 8.
Advanced Techniques (Expert+)
7. X-Wing
A rectangular pattern where a number appears in exactly two cells in two different rows, and those cells are in the same two columns (or vice versa).
Effect: The number can be eliminated from all other cells in those two columns/rows.
8. Y-Wing (XY-Wing)
Three cells forming a Y shape, where one cell has candidates XY, and two others have XZ and YZ. This creates a logical chain that eliminates Z from cells that can see both "wing" cells.
9. Swordfish
Similar to X-Wing but with three rows and three columns. A number appears in at most three cells in three rows, constrained to three columns.
Complexity: This is one of the more complex techniques, requiring careful pattern recognition.
10. Coloring (Simple Coloring)
A technique that uses color coding to track chains of related cells. When you can prove that certain cells must have the same value or different values, you can eliminate candidates.
Logic: If coloring leads to a contradiction (same color in a unit), then the opposite color must be correct.
General Solving Tips
Solving Order
- 1. Start with naked singles
- 2. Look for hidden singles
- 3. Use pencil marks for complex puzzles
- 4. Apply intermediate techniques when stuck
- 5. Try advanced techniques as last resort
Best Practices
- • Work systematically, don't guess
- • Use pencil marks for possibilities
- • Check your work frequently
- • Focus on areas with fewer possibilities
- • Take breaks when stuck
Practice makes perfect!
Apply these techniques to real puzzles, or let our AI solver handle the hard work for you.