Start with the idea
Start with one number. In this example, rows 2 and 7 each need a 6, and their only possible 6s are in the same two columns. Those columns are reserved for those two 6s, so other 6s in those columns cannot be correct.
Look for this pattern
Look for one number that lines up across matching rows and columns.
This empty board keeps the puzzle numbers out of the way so the pattern is easier to see.
Example
5
3
7
6
1
9
5
6
9
8
8
2
6
9
3
4
3
1
6
8
7
2
6
2
6
4
1
9
5
8
7
Look here firstFocus on the number 6. In rows 2 and 7, the only possible 6s are in the same two columns.
This technique reviews candidates instead of solving a square right away.
The 6s for those rows must land in those two columns, so other 6 notes in those columns cannot be correct.
- Choose one number.
- Find two rows with that number in the same two columns.
- Remove that number from the other cells in those columns.
6s in the X-Wing6 notes to remove
When to look for it
Use it when a repeated note lines up as a clean rectangle across two rows or two columns.
How to use it
- Pick one digit and scan rows or columns.
- Find two rows where the digit appears in the same two columns.
- Remove the digit from other cells in those two columns.
Common mistakes
- The two starting rows must each have exactly two notes for the digit.
- The same idea works with rows and columns swapped.