Box Brain Sudoku
Learn › X-Wing
Hard · technique 15 of 18
X-Wing
In two rows, a digit fits in exactly two cells, and those cells line up in the same two columns.
How it works
The digit must take opposite corners of the rectangle, so remove it from the rest of both columns (or rows, the other way round).
A worked example
X-Wing: 4 appears in row 3 and row 9 only within 2 columns, so 4 is removed from those columns elsewhere.
- The rows and columns to look at
- The cells that make the pattern
- Candidates it rules out
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 X-Wing 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.