Box Brain Sudoku
Learn › Naked Single
Easy · technique 1 of 18
Naked Single
A cell has only one candidate left. Also called a sole candidate.
How it works
Note every digit each cell could still take. When a cell is down to one, that digit is the answer.
A worked example
Naked single: the cell in row 5, column 6 has only one candidate left, so it must be 8.
- The cells that make the pattern
- The digit it places
A real position from a puzzle in the app. Small digits are the candidates the step looks at; coloured digits are already solved.
Practise it in Box Brain Sudoku
The app teaches Naked Single on this same board, then hands you puzzles that need it. When you are stuck mid-game, a hint first points you to the right area, then names the technique and shows the move.