Sudoku Techniques

Six techniques finish every level on PeerPuzzles. Learn them in this order. The first two place digits; the rest rule digits out of your notes until one of the first two can place something. Each page shows its technique on the same Hard puzzle, at the moment it’s needed, so you can follow one solve from page to page.

The Hard puzzle every technique page follows: 26 givens, and every technique on this page needed to finish it.

How many of our levels need each one, out of 50 at each difficulty:

Technique	Easy	Medium	Hard
Hidden singles	All 50	All 50	All 50
Naked singles	None	45	40
Pointing pairs	None	10	45
Box/line reduction	None	3	12
Naked pairs	None	None	37
Hidden pairs	None	None	17

“Needed” means nothing simpler would do at that point in the solve. For all six in one place, with a full worked puzzle, see how to solve Sudoku.

Guides

Sudoku Hidden Singles: Find the Only Place for a DigitA hidden single is a digit with only one place left in a row, column or box. How to find them fast, why they're hidden, and how far they take you.
Sudoku Naked Singles: The Only Digit Left for a CellA naked single is a cell with only one possible digit left. How to spot one, why Hard puzzles depend on them, and how notes uncover them.
Sudoku Pointing Pairs and Box/Line ReductionWhen a digit's places in a box all line up, the rest of that line can't have it, and the reverse. Pointing pairs and box/line reduction, with real examples.
Sudoku Naked Pairs: Two Cells, Two DigitsTwo cells in a row, column or box with the same two notes take both digits between them. How naked pairs work, with an example from a real Hard puzzle.
Sudoku Hidden Pairs: Two Digits, Two PlacesWhen two digits share the same two places in a row, column or box, those cells hold them and nothing else. How hidden pairs work, with a real Hard example.