Sudoku guides
Learn Sudoku
Learn Sudoku techniques with worked examples.
Solving skills
Basic techniques
Start with candidates, naked singles and hidden singles.
Read the rules
Sudoku candidates
Find candidates from the row, column and box, then use them to make a deduction.
Naked singles
Use row, column and box constraints to find a cell with one candidate.
Hidden singles
Find the only place for a digit in a row, column or box.
Candidate eliminations
Learn to eliminate candidates
Locked candidates
Use box-line intersections to eliminate candidates.
Examples and practice →
Naked pairs
Two cells with the same two candidates.
Examples and practice →
Hidden pairs
Two digits with the same two possible cells.
Examples and practice →
Puzzle diagnosis
Check puzzle problems
Learn to distinguish conflicts, no solution and multiple solutions.