How to Solve Sudoku
A complete guide to Sudoku solving techniques — from the basics to advanced strategies.
1 Sudoku Rules
- ✓ A standard Sudoku puzzle is a 9×9 grid divided into nine 3×3 boxes. The goal is to fill every cell with a digit from 1 to 9 such that each digit appears exactly once in every row, every column, and every 3×3 box.
2 1. Naked Single (Last Remaining Cell)
- 💡 The simplest technique. If a cell has only one possible digit after eliminating all digits already present in the same row, column, and box, that digit must go in that cell.
3 2. Hidden Single
- 💡 A digit that can only go in one cell within a row, column, or box — even if that cell has other candidates. Place it there immediately.
4 3. Naked Pairs & Triples
- 💡 If two cells in the same unit share the same two candidates and no others, those candidates can be eliminated from all other cells in that unit. This extends to triples (three cells, three candidates).
5 4. Pointing Pairs
- 💡 If a candidate in a box is restricted to one row or column within that box, it can be eliminated from the rest of that row or column outside the box.
6 5. X-Wing
- 💡 An advanced technique. If a candidate appears in exactly two cells in each of two rows, and those cells are in the same two columns, the candidate can be eliminated from all other cells in those two columns.
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Practical Tips
- ✓ Always start with the boxes, rows, or columns that have the most given numbers — they have the fewest possible placements.
- ✓ Use pencil marks (candidate lists) to track which digits are possible in each cell.
- ✓ Scan the entire grid before making a placement — a clue in one area often unlocks another.
- ✓ Work systematically, house by house (row/column/box), rather than jumping around.
- 💡 If you get stuck, try our Sudoku Solver to find the next step.
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