Sudoku Strategy Guide — From Beginner to Expert Level

Sudoku is a logic puzzle, not a math puzzle. You never need arithmetic. Every valid Sudoku has a unique solution discoverable entirely through elimination and logic. Guessing is never required if you have the right techniques.

Basic Technique: Single Candidate

If a cell can only contain one number, fill it in. Work through every empty cell looking for single candidates first. Easy Sudokus are often entirely solvable through this technique alone.

Hidden Singles

If a number can only go in one cell within a row, column, or box, place it there even if that cell has other possible values. Scan each unit for numbers that appear in only one valid position.

Naked Pairs

If two cells in the same unit can only contain the same two numbers, those numbers are reserved exclusively for those two cells. You can eliminate both numbers from all other cells in that unit.

X-Wing Technique

The X-wing applies when a candidate number appears in exactly two cells in each of two rows, and those cells share the same two columns. The number must appear diagonally opposite, allowing elimination from the rest of both columns. This is the gateway to advanced Sudoku solving.