Step-by-step solution
Steps 65
Estimated time 104 – 156 min
Hardest technique X-Wing
Clues 24
Given digit (clue)
Solved digit
Placement (✓ RlCc=d)
Elimination (✗ RlCc≠d)
Look at cell R2C1.
Every other digit already appears in its row, column or box.
Only one option remains: R2C1 = 7.
Look at cell R1C1.
Every other digit already appears in its row, column or box.
Only one option remains: R1C1 = 6.
Look at cell R1C3.
Every other digit already appears in its row, column or box.
Only one option remains: R1C3 = 5.
Look at cell R2C2.
Every other digit already appears in its row, column or box.
Only one option remains: R2C2 = 8.
Look at cell R3C3.
Every other digit already appears in its row, column or box.
Only one option remains: R3C3 = 9.
Scan the empty cells in this row where 1 could go.
Across the whole row, 1 has only one possible spot left.
So R1C4 = 1.
Scan the empty cells in this box where 2 could go.
Across the whole box, 2 has only one possible spot left.
So R1C8 = 2.
Scan the empty cells in this box where 2 could go.
Across the whole box, 2 has only one possible spot left.
So R2C6 = 2.
Scan the empty cells in this box where 1 could go.
Across the whole box, 1 has only one possible spot left.
So R4C6 = 1.
Scan the empty cells in this box where 8 could go.
Across the whole box, 8 has only one possible spot left.
So R5C6 = 8.
Scan the empty cells in this row where 2 could go.
Across the whole row, 2 has only one possible spot left.
So R5C9 = 2.
Scan the empty cells in this box where 5 could go.
Across the whole box, 5 has only one possible spot left.
So R6C6 = 5.
Scan the empty cells in this box where 8 could go.
Across the whole box, 8 has only one possible spot left.
So R6C8 = 8.
Scan the empty cells in this box where 1 could go.
Across the whole box, 1 has only one possible spot left.
So R6C9 = 1.
Scan the empty cells in this box where 2 could go.
Across the whole box, 2 has only one possible spot left.
So R7C1 = 2.
Scan the empty cells in this column where 5 could go.
Across the whole column, 5 has only one possible spot left.
So R7C2 = 5.
Scan the empty cells in this row where 8 could go.
Across the whole row, 8 has only one possible spot left.
So R7C4 = 8.
Scan the empty cells in this box where 1 could go.
Across the whole box, 1 has only one possible spot left.
So R7C5 = 1.
Scan the empty cells in this box where 2 could go.
Across the whole box, 2 has only one possible spot left.
So R8C4 = 2.
Scan the empty cells in this box where 9 could go.
Across the whole box, 9 has only one possible spot left.
So R8C5 = 9.
Scan the empty cells in this row where 8 could go.
Across the whole row, 8 has only one possible spot left.
So R3C9 = 8.
Scan the empty cells in this row where 1 could go.
Across the whole row, 1 has only one possible spot left.
So R5C3 = 1.
Scan the empty cells in this box where 7 could go.
Across the whole box, 7 has only one possible spot left.
So R9C5 = 7.
Scan the empty cells in this column where 7 could go.
Across the whole column, 7 has only one possible spot left.
So R4C2 = 7.
Scan the empty cells in this row where 7 could go.
Across the whole row, 7 has only one possible spot left.
So R6C4 = 7.
(1) Spot R8C1 and R8C6 on this row. (2) Spot R1C7 and R1C9 in this box.
(1) These two cells can only hold 3 and 4: they reserve those digits. (2) These two cells can only hold 4 and 7: they reserve those digits.
(1) 3 and 4 are therefore removed from the other cells of the row. (2) 4 and 7 are therefore removed from the other cells of the box.
Look at where 4 can go on this row.
All its spots lie within a single box (R7C7, R7C8 and R7C9).
4 is therefore removed from the rest of the box.
Find 6 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 6.
R4C9 is seen by both free ends: 6 is therefore eliminated there.
Look at where 6 can go on this column.
All its spots lie within a single box (R8C9 and R9C9).
6 is therefore removed from the rest of the box.
Look at cell R8C8.
Every other digit already appears in its row, column or box.
Only one option remains: R8C8 = 5.
Scan the empty cells in this box where 9 could go.
Across the whole box, 9 has only one possible spot left.
So R2C8 = 9.
Scan the empty cells in this column where 5 could go.
Across the whole column, 5 has only one possible spot left.
So R2C9 = 5.
Scan the empty cells in this box where 4 could go.
Across the whole box, 4 has only one possible spot left.
So R3C4 = 4.
Scan the empty cells in this row where 5 could go.
Across the whole row, 5 has only one possible spot left.
So R3C5 = 5.
Look at cell R2C5.
Every other digit already appears in its row, column or box.
Only one option remains: R2C5 = 3.
Spot R5C2 and R5C5 on this row.
These two cells can only hold 4 and 6: they reserve those digits.
4 and 6 are therefore removed from the other cells of the row.
Look at where 4 can go on this row.
All its spots lie within a single box (R4C8 and R4C9).
4 is therefore removed from the rest of the box.
Spot R3C7 and R6C7 on this column.
These two cells can only hold 3 and 6: they reserve those digits.
3 and 6 are therefore removed from the other cells of the column.
Look at cell R5C7.
Every other digit already appears in its row, column or box.
Only one option remains: R5C7 = 9.
Look at cell R5C4.
Every other digit already appears in its row, column or box.
Only one option remains: R5C4 = 3.
Look at cell R4C4.
Every other digit already appears in its row, column or box.
Only one option remains: R4C4 = 9.
Scan the empty cells in this row where 9 could go.
Across the whole row, 9 has only one possible spot left.
So R7C9 = 9.
Find 3 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 3.
R7C8 is seen by both free ends: 3 is therefore eliminated there.
Look at cell R7C8.
Every other digit already appears in its row, column or box.
Only one option remains: R7C8 = 4.
Look at cell R7C7.
Every other digit already appears in its row, column or box.
Only one option remains: R7C7 = 7.
Look at cell R8C9.
Every other digit already appears in its row, column or box.
Only one option remains: R8C9 = 6.
Look at cell R9C9.
Every other digit already appears in its row, column or box.
Only one option remains: R9C9 = 3.
Look at cell R1C7.
Every other digit already appears in its row, column or box.
Only one option remains: R1C7 = 4.
Look at cell R1C9.
Every other digit already appears in its row, column or box.
Only one option remains: R1C9 = 7.
Look at cell R4C9.
Every other digit already appears in its row, column or box.
Only one option remains: R4C9 = 4.
Look at cell R7C3.
Every other digit already appears in its row, column or box.
Only one option remains: R7C3 = 3.
Look at cell R8C1.
Every other digit already appears in its row, column or box.
Only one option remains: R8C1 = 4.
Look at cell R8C3.
Every other digit already appears in its row, column or box.
Only one option remains: R8C3 = 7.
Look at cell R8C6.
Every other digit already appears in its row, column or box.
Only one option remains: R8C6 = 3.
Look at cell R9C2.
Every other digit already appears in its row, column or box.
Only one option remains: R9C2 = 6.
Look at cell R9C6.
Every other digit already appears in its row, column or box.
Only one option remains: R9C6 = 4.
Look at cell R4C3.
Every other digit already appears in its row, column or box.
Only one option remains: R4C3 = 6.
Look at cell R4C8.
Every other digit already appears in its row, column or box.
Only one option remains: R4C8 = 3.
Look at cell R5C2.
Every other digit already appears in its row, column or box.
Only one option remains: R5C2 = 4.
Look at cell R5C5.
Every other digit already appears in its row, column or box.
Only one option remains: R5C5 = 6.
Look at cell R6C1.
Every other digit already appears in its row, column or box.
Only one option remains: R6C1 = 3.
Look at cell R6C5.
Every other digit already appears in its row, column or box.
Only one option remains: R6C5 = 4.
Look at cell R6C7.
Every other digit already appears in its row, column or box.
Only one option remains: R6C7 = 6.
Look at cell R3C7.
Every other digit already appears in its row, column or box.
Only one option remains: R3C7 = 3.
Look at cell R3C8.
Every other digit already appears in its row, column or box.
Only one option remains: R3C8 = 6.