Sudoku Strategies

Good Sudoku solving is not guessing. It is a chain of small logical deductions based on rows, columns, boxes, and candidates.

Naked singles

If a cell has only one legal candidate after checking its row, column, and box, that digit must go there.

Hidden singles

If a digit can appear in only one cell within a row, column, or box, that cell must take the digit even when it has other candidates.

Locked candidates

When all possible positions for a digit inside a box lie on one row or column, you can remove that digit from the rest of that row or column.

Naked pairs

Two cells sharing the exact same two candidates can remove those candidates from other cells in the same unit.

Return to online Sudoku and practice these strategies while you play.