Sudoku Techniques
Learn strategies to solve even the hardest Sudoku puzzles.
Naked Singles
A cell where only one number can possibly go.
Hidden Singles
A number that can only go in one cell within a row, column, or box.
Naked Pairs
Two cells in the same group with exactly the same two candidates.
Pointing Pairs
Candidates in a box confined to a single row or column.
Box/Line Reduction
Candidates in a row or column confined to a single box.
X-Wing
A pattern of four cells forming a rectangle that eliminates candidates.
Swordfish
An extension of X-Wing using three rows and three columns.
XY-Wing
Three cells with paired candidates that eliminate a common candidate.