GridWits
Hard tier Technique 11 of 46 Used by Smart Hint

X-Wing

A digit's candidates in two rows fall in the exact same two columns, forming a rectangle — eliminate it from the rest of those columns.

How it works

  1. 1Digit 4 only fits in columns C and G in both row 2 and row 3 — nowhere else in either row.
  2. 2That locks 4 into a rectangle across those two rows and two columns. Whichever row takes column C, the other must take column G — so 4 can be crossed off columns C and G in every other row, including row 6, at C6 and G6.

Play a Sudoku that needs this technique →

A 1 B 2 C 3 D 4 E 5 F 6 G 7 H 8 I 9 7 4 8 9 1 4 6 4 5 1 3 4 2 4 7 8 4 9 4 4 4 4 4 4
  • Cells that establish the pattern
  • Where the conclusion lands
  • Candidate ruled out
Next in the ladder XY-Wing →

A pivot cell and two "wing" cells, each sharing one candidate with the pivot, corner a shared digit out of any cell both wings can see.