Sudoku365
Sudoku Strategy & Solving Techniques
Every Sudoku is solvable with logic alone. These tutorials walk through the techniques in the order most solvers learn them — starting with basic scanning moves that unlock Easy puzzles, then building up to the patterns needed for Hard and Expert grids.
Work through the tutorials in order if you are new to the game. If you already know the basics, jump ahead: each tutorial is self-contained and worked through with examples.
Beginner Techniques
These are the foundations. Easy puzzles can often be solved using these techniques alone.
Naked Singles
Find cells where only one digit can fit given the contents of the row, column, and box.
Hidden Singles
Look at where a specific digit can go within a row, column, or box — often there is only one option.
Scanning Technique
The systematic eye-movement pattern that lets you spot singles quickly without writing anything down.
Intermediate Techniques
These show up regularly in Medium and Hard puzzles. They usually need pencil marks to apply reliably.
Naked Pairs
When two cells in a unit share exactly the same two candidates, those candidates can be removed from every other cell in the unit.
Hidden Pairs
When two digits can only go in two cells of a unit, those two cells must hold that pair — even if they currently show other candidates.
Locked Candidates
Also called Pointing and Claiming. Use the overlap between a box and a line to eliminate candidates from either.
Advanced Techniques
Expert puzzles rarely yield without these. Each relies on an elimination pattern spanning several rows or columns at once.
X-Wing Pattern
Four cells forming a rectangle let you eliminate a candidate along two rows or two columns.
Swordfish Pattern
A three-row extension of X-Wing. Harder to spot, but powerful when the grid has a stubborn shape.
Y-Wing Chain
A three-cell logical chain that eliminates a candidate from any cell that sees the two endpoints.
General Solving Tips
- Start with scanning: Always sweep for naked and hidden singles before committing to pencil marks.
- Use pencil marks deliberately: Only mark cells once scanning runs out. Marks everywhere at once make the grid hard to read.
- Work one technique at a time: After each deduction, re-scan for singles before moving on.
- Focus on constrained areas: Boxes and lines that already have many digits are the most likely to yield the next move.
- Practice daily: Pattern recognition is a trained skill. Regular solving is worth more than occasional long sessions.
Choosing the Right Technique
Different difficulty levels usually need different strategies:
- Easy puzzles: Naked singles and basic scanning are often enough.
- Medium puzzles: Add hidden singles and naked pairs to your toolkit.
- Hard puzzles: Locked candidates and pointing pairs become necessary.
- Expert puzzles: Expect to reach for X-Wing, Swordfish, and Y-Wing.
Ready to try? Open today's puzzle and apply a technique or two.
Last reviewed on April 23, 2026.