The ‘X-Wing’ technique is an advanced Sudoku technique that focuses on two parallel rows or columns and does not involve 3×3 blocks.
As shown in the first image, consider two parallel rows, each with two cells containing a candidate number 4. Given that 4 cannot repeat in the same row or column, we can deduce that the 4s must be placed diagonally—either in the green-framed cells or in the red-framed cells. These diagonals form a virtual ‘X’.
Now, as shown in the second image, if we shift our focus to the columns that intersect these rows, we observe that the diagonal placement ensures a 4 in each column. Consequently, this placement rules out any other possible placements of 4 in these columns. Therefore, we can confidently eliminate 4 from all other candidate cells in these columns as highlighted with the purple frame.
By applying the ‘X-Wing’ technique, you effectively narrow down the placement possibilities by eliminating other candidate numbers. Download our free printable Sudoku puzzle books and have more fun.