Sudoku techniques
These are the techniques the puzzles in Sudoku Arena are built around, from the two that solve every Easy puzzle to the ones that make Extreme puzzles extreme. Each page explains the logic, shows a real position from one of our puzzles where the technique is the next move, and lets you play that puzzle.
| Technique | First needed in | In one line |
|---|---|---|
| Naked Single | Easy | A cell where only one number is still possible. |
| Hidden Single | Easy | A number that fits in only one cell of a row, column or box. |
| Pointing Pair | Hard / Expert | Inside a box, a number is limited to one row or column, so it is removed from the rest of that line. |
| Box/Line Reduction | Expert | In a row or column, a number fits only inside one box, so it is removed from the rest of that box. |
| Naked Pair | Expert | Two cells in a unit share the same two candidates, so those numbers are removed from the rest of the unit. |
| Naked Triple (and Quad) | Master | Three cells in a unit use only three numbers between them, so those numbers are removed from the rest of the unit. |
| Hidden Pair | Master | Two numbers that can only go in the same two cells of a unit; every other candidate in those cells is removed. |
| Hidden Triple | Master / Extreme | Three numbers restricted to the same three cells of a unit; other candidates in those cells go. |
| X-Wing | Extreme | A number fits in two rows only in the same two columns, so it is removed from the rest of those columns. |
| Swordfish | Extreme | An X-Wing with three rows and three columns. |
| XY-Wing | Extreme | Three two-candidate cells (a pivot and two pincers) remove a number from cells that see both pincers. |
| XYZ-Wing | Extreme | Like an XY-Wing, but the pivot also holds Z; removals happen in cells that see all three. |
How to use this guide
- Learn them in order. Each technique builds on the ones before it, and harder puzzles still need all the easy moves.
- Always look for singles first. Even in Extreme puzzles most moves are naked and hidden singles.
- Use notes from Expert level up. Every technique after the singles is about candidates, and they are much easier to see when written down.
- Stuck in a game? A hint in Sudoku Arena names the technique it used, so you can come back here and read about it.
New to Sudoku? Start with how to play, or read the shorter overview of solving strategies.