Sudoku Strategy Guide: 7 Techniques Every Solver Should Know

Most Sudoku puzzles can be solved with a handful of techniques. Learn these seven and you'll clear beginner and intermediate boards without guessing. Practice them on our daily Sudoku.

1. Naked singles

A cell where eight of nine digits are already ruled out by its row, column, and box. Fill it in. This is the first technique you'll use on almost every board.

2. Hidden singles

Scan a row, column, or 3×3 box for a digit that can only go in one cell — even if that cell has other candidates. Faster than naked singles once your eyes learn the pattern.

3. Naked pairs

Two cells in the same unit whose only candidates are the same two digits. Those digits can be eliminated from every other cell in that unit.

4. Hidden pairs

Two digits that can only appear in the same two cells inside a unit. Every other candidate can be removed from those two cells.

5. Pointing pairs and triples

When a digit's candidates in a 3×3 box all sit in one row or column, that digit can be eliminated from the rest of that row or column outside the box.

6. Box/line reduction

The mirror image of pointing pairs: when a digit's candidates in a row or column all sit in one 3×3 box, the digit can be eliminated from the rest of that box.

7. X-Wing

When a candidate appears in only two cells across two rows, and those cells share the same two columns, the candidate can be eliminated from every other cell in those two columns. Your first "advanced" technique.

Practice makes fast

These techniques scale to almost every hard puzzle. If you want more logic games to try, see our best logic puzzle games roundup, or check today's daily challenge.