Step-by-step solution
Steps 68
Estimated time 112 – 168 min
Hardest technique X-Wing
Clues 22
Given digit (clue)
Solved digit
Placement (✓ RlCc=d)
Elimination (✗ RlCc≠d)
Scan the empty cells in this column where 9 could go.
Across the whole column, 9 has only one possible spot left.
So R2C3 = 9.
Scan the empty cells in this row where 3 could go.
Across the whole row, 3 has only one possible spot left.
So R2C8 = 3.
Scan the empty cells in this box where 9 could go.
Across the whole box, 9 has only one possible spot left.
So R4C2 = 9.
Scan the empty cells in this column where 3 could go.
Across the whole column, 3 has only one possible spot left.
So R5C7 = 3.
Scan the empty cells in this box where 2 could go.
Across the whole box, 2 has only one possible spot left.
So R5C9 = 2.
Scan the empty cells in this box where 3 could go.
Across the whole box, 3 has only one possible spot left.
So R6C2 = 3.
Scan the empty cells in this box where 2 could go.
Across the whole box, 2 has only one possible spot left.
So R7C4 = 2.
Scan the empty cells in this box where 7 could go.
Across the whole box, 7 has only one possible spot left.
So R7C5 = 7.
Scan the empty cells in this column where 4 could go.
Across the whole column, 4 has only one possible spot left.
So R8C4 = 4.
Scan the empty cells in this box where 3 could go.
Across the whole box, 3 has only one possible spot left.
So R8C5 = 3.
Scan the empty cells in this box where 2 could go.
Across the whole box, 2 has only one possible spot left.
So R8C7 = 2.
Scan the empty cells in this box where 3 could go.
Across the whole box, 3 has only one possible spot left.
So R9C1 = 3.
Scan the empty cells in this box where 4 could go.
Across the whole box, 4 has only one possible spot left.
So R9C8 = 4.
Scan the empty cells in this box where 8 could go.
Across the whole box, 8 has only one possible spot left.
So R1C3 = 8.
Scan the empty cells in this box where 8 could go.
Across the whole box, 8 has only one possible spot left.
So R2C9 = 8.
Scan the empty cells in this column where 2 could go.
Across the whole column, 2 has only one possible spot left.
So R3C1 = 2.
Scan the empty cells in this box where 8 could go.
Across the whole box, 8 has only one possible spot left.
So R3C5 = 8.
Scan the empty cells in this box where 7 could go.
Across the whole box, 7 has only one possible spot left.
So R4C8 = 7.
Scan the empty cells in this column where 7 could go.
Across the whole column, 7 has only one possible spot left.
So R6C4 = 7.
Scan the empty cells in this row where 7 could go.
Across the whole row, 7 has only one possible spot left.
So R8C3 = 7.
Scan the empty cells in this row where 2 could go.
Across the whole row, 2 has only one possible spot left.
So R9C2 = 2.
Scan the empty cells in this box where 4 could go.
Across the whole box, 4 has only one possible spot left.
So R1C2 = 4.
Scan the empty cells in this box where 6 could go.
Across the whole box, 6 has only one possible spot left.
So R1C5 = 6.
Scan the empty cells in this column where 7 could go.
Across the whole column, 7 has only one possible spot left.
So R1C9 = 7.
Scan the empty cells in this row where 7 could go.
Across the whole row, 7 has only one possible spot left.
So R2C1 = 7.
Scan the empty cells in this row where 6 could go.
Across the whole row, 6 has only one possible spot left.
So R3C2 = 6.
Scan the empty cells in this box where 4 could go.
Across the whole box, 4 has only one possible spot left.
So R3C7 = 4.
Spot R4C5 and R6C6 in this box.
These two cells can only hold 1 and 5: they reserve those digits.
1 and 5 are therefore removed from the other cells of the box.
Look at cell R5C5.
Every other digit already appears in its row, column or box.
Only one option remains: R5C5 = 9.
Find 5 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 5.
R3C8 and R4C7 is seen by both free ends: 5 is therefore eliminated there.
Find 5 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 5.
R4C1 and R6C6 is seen by both free ends: 5 is therefore eliminated there.
Look at cell R6C6.
Every other digit already appears in its row, column or box.
Only one option remains: R6C6 = 1.
Look at cell R4C5.
Every other digit already appears in its row, column or box.
Only one option remains: R4C5 = 5.
Look at cell R9C5.
Every other digit already appears in its row, column or box.
Only one option remains: R9C5 = 1.
Look at where 5 can go in this box.
All its spots lie on a single column (R5C8 and R6C8).
5 is therefore removed from that column outside 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.
R9C9 is seen by both free ends: 6 is therefore eliminated there.
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.
R7C8 is seen by both free ends: 6 is therefore eliminated there.
Look at where 6 can go in this box.
All its spots lie on a single row (R8C8 and R8C9).
6 is therefore removed from that row outside the box.
Look at cell R8C6.
Every other digit already appears in its row, column or box.
Only one option remains: R8C6 = 5.
Spot R4C9 and R8C9 on this column.
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 column.
Find 5 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 5.
R1C1 is seen by both free ends: 5 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 R1C7.
Every other digit already appears in its row, column or box.
Only one option remains: R1C7 = 5.
Look at cell R2C2.
Every other digit already appears in its row, column or box.
Only one option remains: R2C2 = 5.
Look at cell R2C4.
Every other digit already appears in its row, column or box.
Only one option remains: R2C4 = 1.
Look at cell R3C4.
Every other digit already appears in its row, column or box.
Only one option remains: R3C4 = 5.
Look at cell R3C9.
Every other digit already appears in its row, column or box.
Only one option remains: R3C9 = 9.
Look at cell R9C9.
Every other digit already appears in its row, column or box.
Only one option remains: R9C9 = 5.
Look at cell R3C8.
Every other digit already appears in its row, column or box.
Only one option remains: R3C8 = 1.
Look at cell R9C3.
Every other digit already appears in its row, column or box.
Only one option remains: R9C3 = 6.
Look at cell R9C6.
Every other digit already appears in its row, column or box.
Only one option remains: R9C6 = 9.
Look at cell R6C3.
Every other digit already appears in its row, column or box.
Only one option remains: R6C3 = 5.
Look at cell R6C8.
Every other digit already appears in its row, column or box.
Only one option remains: R6C8 = 6.
Look at cell R7C1.
Every other digit already appears in its row, column or box.
Only one option remains: R7C1 = 5.
Look at cell R7C6.
Every other digit already appears in its row, column or box.
Only one option remains: R7C6 = 6.
Look at cell R8C8.
Every other digit already appears in its row, column or box.
Only one option remains: R8C8 = 8.
Look at cell R4C9.
Every other digit already appears in its row, column or box.
Only one option remains: R4C9 = 1.
Look at cell R5C1.
Every other digit already appears in its row, column or box.
Only one option remains: R5C1 = 4.
Look at cell R5C6.
Every other digit already appears in its row, column or box.
Only one option remains: R5C6 = 8.
Look at cell R5C8.
Every other digit already appears in its row, column or box.
Only one option remains: R5C8 = 5.
Look at cell R7C7.
Every other digit already appears in its row, column or box.
Only one option remains: R7C7 = 1.
Look at cell R7C8.
Every other digit already appears in its row, column or box.
Only one option remains: R7C8 = 9.
Look at cell R8C2.
Every other digit already appears in its row, column or box.
Only one option remains: R8C2 = 1.
Look at cell R8C9.
Every other digit already appears in its row, column or box.
Only one option remains: R8C9 = 6.
Look at cell R4C1.
Every other digit already appears in its row, column or box.
Only one option remains: R4C1 = 6.
Look at cell R4C6.
Every other digit already appears in its row, column or box.
Only one option remains: R4C6 = 4.
Look at cell R4C7.
Every other digit already appears in its row, column or box.
Only one option remains: R4C7 = 8.
Look at cell R7C2.
Every other digit already appears in its row, column or box.
Only one option remains: R7C2 = 8.