How to Play Sudoku
A complete guide to understanding and mastering Sudoku, from basic rules to advanced techniques.
What is Sudoku?
Sudoku is a logic-based number puzzle that originated in Japan. The goal is to fill a 9x9 grid with digits so that each column, each row, and each of the nine 3x3 subgrids contain all of the digits from 1 to 9 without repetition.
The Three Basic Rules
- 1.Each row must contain the numbers 1-9, with no repetition.
- 2.Each column must contain the numbers 1-9, with no repetition.
- 3.Each 3x3 box must contain the numbers 1-9, with no repetition.
Sudoku Solving Strategies
Learning Sudoku teaches you 9 professional solving techniques. Here's an overview of each:
Basic Techniques
Naked Single
When a cell has only one possible candidate remaining, that number must go in that cell.
Hidden Single
When a number can only go in one cell within a row, column, or box, it must go there.
Intermediate Techniques
Naked Pair
When two cells in a unit contain the same two candidates, those numbers can be eliminated from other cells in that unit.
Hidden Pair
When two numbers can only appear in two cells within a unit, all other candidates can be removed from those cells.
Pointing Pair
When a candidate appears only in one row or column within a box, it can be eliminated from that row/column outside the box.
Box/Line Reduction
When a candidate in a row/column is confined to a single box, it can be eliminated from other cells in that box.
Advanced Techniques
X-Wing
A pattern using two rows and two columns where a candidate appears exactly twice in each row, allowing eliminations.
Swordfish
An extension of X-Wing using three rows and three columns, creating a powerful elimination pattern.
XY-Wing
Uses three cells with two candidates each, connected in a chain, to eliminate candidates from cells that see all three.
Tips for Success
Start with Easy Puzzles
Build your confidence by solving easier puzzles first. As you improve, gradually increase the difficulty.
Use Pencil Marks
Write down all possible candidates in each cell. This helps you spot patterns and eliminate options.
Scan Systematically
Check each row, column, and box methodically. Don't jump around randomly looking for solutions.
Learn One Technique at a Time
Master each technique before moving to the next. Learning Sudoku's hint system can guide you through this process.
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