X-Wing
A value's only two candidate cells line up in the same two columns (or rows) across two rows (or columns) — eliminate it everywhere else in those columns or rows.
How it works
- 1In row 1 and row 3, digit 4 has only two possible columns: column 2 and column 4.
- 2Each of those rows must place one 4. Whichever row uses column 2 forces the other row to use column 4, forming the four corners of an X-Wing.
- 3Those two columns have their 4s reserved by the pattern rows, so remove 4 from the same columns in every other row — including both marked cells in row 5.
- Candidates this technique rules out
- Cells read together — The connecting line shows which cells combine to make the deduction.
- Conclusion — The coloured candidate, or the final arrow when it lands outside the pattern, shows the result.