Master scanning before advanced patterns
Advanced names like X-Wing and Swordfish are useful later, but most beginner and medium Sudoku puzzles can be solved with careful scanning and candidate elimination.
If you skip the basics, advanced techniques feel like memorized tricks instead of logical extensions.
Naked singles
A naked single happens when a cell has only one possible number left. This is the safest move in Sudoku because the row, column, and box already rule out every other number.
Hidden singles
A hidden single happens when a number has only one possible position inside a row, column, or box. The cell may appear to have several candidates, but the unit itself gives the answer.
Candidate cleanup
After every confirmed placement, remove that number from notes in the same row, column, and box. Many puzzles become easier simply because the notes stay accurate.
- Update notes after every solved cell.
- Scan one 3x3 box at a time.
- Avoid long chains until basic candidates are clean.
- Use hints as a learning tool, not as a replacement for checking.