Naked Single
The Naked Single is categorized as a solving technique but you can hardly call it a technique. A naked single is that what remains after you have applied your solving techniques, by eliminating other candidates.
A naked single is the last remaining candidate in a cell. Alternative terms are Forced Digit and Sole Candidate.
The easiest way to find naked singles in the grid is using pencilmarks. Cells with a single pencilmark are easy to spot. Without pencilmarks, you need to inspect the peers of the cell and see if there is only a single digit missing in the peers. You need a good short-term memory to do it this way, but many players prefer to solve easy Sudokus without pencilmarks.
Most players do not mention the discovery of singles to other players. When a Sudoku can be solved with singles only, the entire puzzle is not worth a discussion.
Example
The following Sudoku has two Naked Singles for digit 8.
The following six puzzles can be solved by only placing naked singles when using pencilmarks.
..........1.2.3.4....456....47...89...2.7.6...98...75....684....3.7.1.6.......... ..4...9...37...54.19.....38...1.3......589......2.4...46.....89.12...36...5...7.. 1.2...3.......4.5.5.6.2...7...1...4...5...8...3...6...7...9.1.8.8.3.......4...9.6 ......1......2..34..3.5.67..1...2..8..4.6.5..3..1...2..95.4.8..68..1......2...... ......9......2..36..8.9.47..7...2..1..4.6.7..6..3...2..92.4.8..38..1......7...... ..9.8.7...6...5.4.3.....5.2.......3.6...7.4...8.......2.7.1...3.4.7...9...5...8..
See also
External links
- Naked Single by Ruud van der Werf
- Forced Cell by Andries E. Brouwer
- Single by Angus Johnson
- Forced Move by Kevin Stone
- Naked Single by Simon Armstrong
- Single-Candidate Square by Paul Stephens
- Single Number by Gaby Vanhegan
- Single Candidate (Lone Number) by Vincent Tandart
- ExperienceSudoku by Christopher Rucinski
