Sudoku Solving Techniques: From Beginner to Advanced
Sudoku is a game of logic, not guessing. Once you know the right techniques, even "hard" puzzles become approachable step by step. Here's a technique ladder from beginner to advanced.
1. Scanning (Beginner)
Scanning means looking at a row, column, or 3x3 box and asking: which numbers are already placed, and which cell is the only one left for a missing number? This is the foundation of nearly every Sudoku solve.
2. Single Candidates
For each empty cell, list which numbers are still legally allowed based on its row, column, and box. If only one number fits, that's a "naked single" — fill it in immediately.
3. Hidden Singles
Sometimes a number can only go in one specific cell within a row, column, or box, even if that cell has other candidates too. Spotting these "hidden singles" is one of the biggest speed boosts for intermediate solvers.
4. Naked Pairs and Triples
When two cells in the same unit share exactly the same two candidate numbers, those two numbers can be eliminated as candidates from every other cell in that unit. The same logic extends to triples with three shared candidates across three cells.
5. Pointing Pairs
If a candidate number appears in only two or three cells within a box, and those cells all fall in the same row or column, you can eliminate that candidate from the rest of that row or column outside the box.
6. Take Notes
For harder puzzles, jotting small candidate numbers in the corner of each cell (pencil marks) is essential. It turns a memory challenge into a visual pattern-matching task.
Building Speed
Speed comes from technique, not guesswork. Solvers who avoid trial-and-error and instead work through scanning, singles, and pairs systematically finish puzzles faster and with fewer mistakes.