The technique map
Sudoku technique map
Browse standard 9 × 9 Sudoku techniques and choose a guide.
Learning path
14 techniques shown.
Read the position
Understand a unit, its peers and the difference between a candidate and a proven answer.
Place a digit
Either one cell has only one choice, or one digit has only one place in a unit.
Connect a box and a line
Confined positions let you eliminate candidates across an intersection.
Reserve cells and digits
Naked subsets look at cells. Hidden subsets look at positions for digits.
Distinguish a mistake from a limit
A duplicate, a puzzle with no solution, multiple solutions and a stalled logical path are different conditions.
Related research
When singles run out →Try locked candidates on the first Hard puzzle in our catalog.
References
HoDoKu and SudokuWiki