Step-by-step solution
Steps 66
Estimated time 108 – 162 min
Hardest technique X-Wing
Clues 23
Given digit (clue)
Solved digit
Placement (✓ RlCc=d)
Elimination (✗ RlCc≠d)
Look at cell R9C6.
Every other digit already appears in its row, column or box.
Only one option remains: R9C6 = 8.
Look at cell R9C3.
Every other digit already appears in its row, column or box.
Only one option remains: R9C3 = 1.
Look at cell R9C9.
Every other digit already appears in its row, column or box.
Only one option remains: R9C9 = 3.
Look at cell R9C1.
Every other digit already appears in its row, column or box.
Only one option remains: R9C1 = 4.
Look at cell R9C5.
Every other digit already appears in its row, column or box.
Only one option remains: R9C5 = 7.
Scan the empty cells in this row where 3 could go.
Across the whole row, 3 has only one possible spot left.
So R2C4 = 3.
Scan the empty cells in this column where 2 could go.
Across the whole column, 2 has only one possible spot left.
So R2C6 = 2.
Scan the empty cells in this box where 4 could go.
Across the whole box, 4 has only one possible spot left.
So R2C9 = 4.
Scan the empty cells in this column where 3 could go.
Across the whole column, 3 has only one possible spot left.
So R3C1 = 3.
Scan the empty cells in this box where 7 could go.
Across the whole box, 7 has only one possible spot left.
So R3C8 = 7.
Scan the empty cells in this column where 4 could go.
Across the whole column, 4 has only one possible spot left.
So R4C2 = 4.
Scan the empty cells in this box where 7 could go.
Across the whole box, 7 has only one possible spot left.
So R4C4 = 7.
Scan the empty cells in this row where 3 could go.
Across the whole row, 3 has only one possible spot left.
So R4C8 = 3.
Scan the empty cells in this row where 4 could go.
Across the whole row, 4 has only one possible spot left.
So R5C7 = 4.
Scan the empty cells in this row where 5 could go.
Across the whole row, 5 has only one possible spot left.
So R6C4 = 5.
Scan the empty cells in this box where 7 could go.
Across the whole box, 7 has only one possible spot left.
So R6C9 = 7.
Scan the empty cells in this row where 7 could go.
Across the whole row, 7 has only one possible spot left.
So R7C2 = 7.
Scan the empty cells in this box where 9 could go.
Across the whole box, 9 has only one possible spot left.
So R7C3 = 9.
Scan the empty cells in this row where 4 could go.
Across the whole row, 4 has only one possible spot left.
So R7C4 = 4.
Scan the empty cells in this box where 3 could go.
Across the whole box, 3 has only one possible spot left.
So R7C5 = 3.
Scan the empty cells in this box where 5 could go.
Across the whole box, 5 has only one possible spot left.
So R7C6 = 5.
Scan the empty cells in this box where 5 could go.
Across the whole box, 5 has only one possible spot left.
So R8C2 = 5.
Scan the empty cells in this box where 9 could go.
Across the whole box, 9 has only one possible spot left.
So R8C4 = 9.
Look at cell R8C5.
Every other digit already appears in its row, column or box.
Only one option remains: R8C5 = 6.
Scan the empty cells in this box where 6 could go.
Across the whole box, 6 has only one possible spot left.
So R4C6 = 6.
Scan the empty cells in this row where 9 could go.
Across the whole row, 9 has only one possible spot left.
So R5C6 = 9.
Spot R7C1 and R8C1 on this column.
These two cells can only hold 2 and 8: they reserve those digits.
2 and 8 are therefore removed from the other cells of the column.
Scan the empty cells in this box where 8 could go.
Across the whole box, 8 has only one possible spot left.
So R4C3 = 8.
Scan the empty cells in this box where 1 could go.
Across the whole box, 1 has only one possible spot left.
So R4C5 = 1.
Scan the empty cells in this row where 8 could go.
Across the whole row, 8 has only one possible spot left.
So R5C4 = 8.
(1) Spot R1C1 and R1C4 on this row. (2) Spot R4C7 and R4C9 in this box.
(1) These two cells can only hold 1 and 6: they reserve those digits. (2) These two cells can only hold 2 and 9: they reserve those digits.
(1) 1 and 6 are therefore removed from the other cells of the row. (2) 2 and 9 are therefore removed from the other cells of the box.
Find where 1 and 6 can go on this column.
These two digits only fit in R3C9 and R7C9 on the column.
The other candidates in R3C9 and R7C9 are therefore eliminated.
Spot R3C4 and R3C9 on this row.
These two cells can only hold 1 and 6: they reserve those digits.
1 and 6 are therefore removed from the other cells of the row.
Find 1 on one row and one column, each with two candidate positions, sharing a box.
The two strands meet in the shared box. One of the two free ends must hold 1.
R2C8 is seen by both free ends: 1 is therefore eliminated there.
Spot R2C3 and R2C8 on this row.
These two cells can only hold 5 and 6: they reserve those digits.
5 and 6 are therefore removed from the other cells of the row.
Find where 1 appears on two rows: altogether, only two columns are involved (R2C2, R2C7, R6C2 and R6C7).
On each covered column, 1 must lie within one of these two rows.
1 is therefore removed from those two columns outside the two X-Wing rows.
Find 6 on two rows, each with exactly two candidate positions.
A shared column connects one end of each pair. Whichever way the logic falls, one of the two free ends must hold 6.
R1C1 and R6C3 is seen by both free ends: 6 is therefore eliminated there.
Look at cell R1C1.
Every other digit already appears in its row, column or box.
Only one option remains: R1C1 = 1.
Look at cell R1C4.
Every other digit already appears in its row, column or box.
Only one option remains: R1C4 = 6.
Look at cell R2C2.
Every other digit already appears in its row, column or box.
Only one option remains: R2C2 = 8.
Look at cell R2C7.
Every other digit already appears in its row, column or box.
Only one option remains: R2C7 = 1.
Look at cell R3C4.
Every other digit already appears in its row, column or box.
Only one option remains: R3C4 = 1.
Look at cell R3C9.
Every other digit already appears in its row, column or box.
Only one option remains: R3C9 = 6.
Look at cell R5C1.
Every other digit already appears in its row, column or box.
Only one option remains: R5C1 = 6.
Look at cell R5C8.
Every other digit already appears in its row, column or box.
Only one option remains: R5C8 = 1.
Look at cell R6C3.
Every other digit already appears in its row, column or box.
Only one option remains: R6C3 = 2.
Look at cell R6C7.
Every other digit already appears in its row, column or box.
Only one option remains: R6C7 = 6.
Look at cell R7C9.
Every other digit already appears in its row, column or box.
Only one option remains: R7C9 = 1.
Look at cell R2C8.
Every other digit already appears in its row, column or box.
Only one option remains: R2C8 = 5.
Look at cell R3C3.
Every other digit already appears in its row, column or box.
Only one option remains: R3C3 = 5.
Look at cell R3C5.
Every other digit already appears in its row, column or box.
Only one option remains: R3C5 = 8.
Look at cell R6C2.
Every other digit already appears in its row, column or box.
Only one option remains: R6C2 = 1.
Look at cell R1C5.
Every other digit already appears in its row, column or box.
Only one option remains: R1C5 = 5.
Look at cell R1C8.
Every other digit already appears in its row, column or box.
Only one option remains: R1C8 = 2.
Look at cell R2C3.
Every other digit already appears in its row, column or box.
Only one option remains: R2C3 = 6.
Look at cell R3C7.
Every other digit already appears in its row, column or box.
Only one option remains: R3C7 = 9.
Look at cell R4C7.
Every other digit already appears in its row, column or box.
Only one option remains: R4C7 = 2.
Look at cell R4C9.
Every other digit already appears in its row, column or box.
Only one option remains: R4C9 = 9.
Look at cell R7C7.
Every other digit already appears in its row, column or box.
Only one option remains: R7C7 = 8.
Look at cell R7C8.
Every other digit already appears in its row, column or box.
Only one option remains: R7C8 = 6.
Look at cell R8C9.
Every other digit already appears in its row, column or box.
Only one option remains: R8C9 = 2.
Look at cell R1C2.
Every other digit already appears in its row, column or box.
Only one option remains: R1C2 = 9.
Look at cell R1C9.
Every other digit already appears in its row, column or box.
Only one option remains: R1C9 = 8.
Look at cell R3C2.
Every other digit already appears in its row, column or box.
Only one option remains: R3C2 = 2.
Look at cell R7C1.
Every other digit already appears in its row, column or box.
Only one option remains: R7C1 = 2.
Look at cell R8C1.
Every other digit already appears in its row, column or box.
Only one option remains: R8C1 = 8.