Step-by-step solution
Steps 65
Estimated time 104 – 156 min
Hardest technique X-Wing
Clues 23
Given digit (clue)
Solved digit
Placement (✓ RlCc=d)
Elimination (✗ RlCc≠d)
Look at cell R6C8.
Every other digit already appears in its row, column or box.
Only one option remains: R6C8 = 3.
Look at cell R5C8.
Every other digit already appears in its row, column or box.
Only one option remains: R5C8 = 2.
Scan the empty cells in this box where 8 could go.
Across the whole box, 8 has only one possible spot left.
So R2C8 = 8.
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 5 could go.
Across the whole box, 5 has only one possible spot left.
So R4C2 = 5.
Scan the empty cells in this row where 8 could go.
Across the whole row, 8 has only one possible spot left.
So R4C7 = 8.
Scan the empty cells in this box where 6 could go.
Across the whole box, 6 has only one possible spot left.
So R5C3 = 6.
Scan the empty cells in this box where 8 could go.
Across the whole box, 8 has only one possible spot left.
So R7C9 = 8.
Scan the empty cells in this box where 8 could go.
Across the whole box, 8 has only one possible spot left.
So R8C4 = 8.
Scan the empty cells in this box where 5 could go.
Across the whole box, 5 has only one possible spot left.
So R9C1 = 5.
Scan the empty cells in this row where 1 could go.
Across the whole row, 1 has only one possible spot left.
So R9C2 = 1.
Scan the empty cells in this column where 8 could go.
Across the whole column, 8 has only one possible spot left.
So R9C3 = 8.
Look at cell R9C8.
Every other digit already appears in its row, column or box.
Only one option remains: R9C8 = 6.
Scan the empty cells in this box where 6 could go.
Across the whole box, 6 has only one possible spot left.
So R1C7 = 6.
Scan the empty cells in this column where 6 could go.
Across the whole column, 6 has only one possible spot left.
So R2C5 = 6.
Scan the empty cells in this box where 5 could go.
Across the whole box, 5 has only one possible spot left.
So R2C7 = 5.
Scan the empty cells in this row where 5 could go.
Across the whole row, 5 has only one possible spot left.
So R1C6 = 5.
Scan the empty cells in this column where 2 could go.
Across the whole column, 2 has only one possible spot left.
So R3C7 = 2.
Scan the empty cells in this column where 6 could go.
Across the whole column, 6 has only one possible spot left.
So R6C4 = 6.
Scan the empty cells in this column where 1 could go.
Across the whole column, 1 has only one possible spot left.
So R6C7 = 1.
(1) Spot R5C5 and R5C7 on this row. (2) Spot R5C7 and R7C7 on this column.
(1) These two cells can only hold 4 and 7: they reserve those digits. (2) These two cells can only hold 4 and 7: they reserve those digits.
(1) 4 and 7 are therefore removed from the other cells of the row. (2) 4 and 7 are therefore removed from the other cells of the column.
Scan the empty cells in this box where 9 could go.
Across the whole box, 9 has only one possible spot left.
So R8C7 = 9.
Scan the empty cells in this row where 3 could go.
Across the whole row, 3 has only one possible spot left.
So R9C7 = 3.
(1) Look at where 7 can go in this box. (2) Look at where 2 can go in this box.
(1) All its spots lie on a single column (R4C1 and R6C1). (2) All its spots lie on a single row (R7C1 and R7C2).
(1) 7 is therefore removed from that column outside the box. (2) 2 is therefore removed from that row outside the box.
Find 7 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 7.
R4C6, R6C6 and R9C5 is seen by both free ends: 7 is therefore eliminated there.
Look at where 7 can go on this column.
All its spots lie within a single box (R4C5 and R5C5).
7 is therefore removed from the rest of the box.
Find 3 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 3.
R1C4 is seen by both free ends: 3 is therefore eliminated there.
Find 4 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 4.
R9C5 is seen by both free ends: 4 is therefore eliminated there.
Look at cell R9C5.
Every other digit already appears in its row, column or box.
Only one option remains: R9C5 = 2.
Spot R4C5 and R5C5 in this box.
These two cells can only hold 4 and 7: they reserve those digits.
4 and 7 are therefore removed from the other cells of the box.
Look at cell R6C6.
Every other digit already appears in its row, column or box.
Only one option remains: R6C6 = 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 R5C2.
Every other digit already appears in its row, column or box.
Only one option remains: R5C2 = 9.
Scan the empty cells in this box where 1 could go.
Across the whole box, 1 has only one possible spot left.
So R1C9 = 1.
Scan the empty cells in this column where 9 could go.
Across the whole column, 9 has only one possible spot left.
So R2C1 = 9.
Scan the empty cells in this box where 3 could go.
Across the whole box, 3 has only one possible spot left.
So R2C9 = 3.
Scan the empty cells in this box where 3 could go.
Across the whole box, 3 has only one possible spot left.
So R3C6 = 3.
Scan the empty cells in this row where 9 could go.
Across the whole row, 9 has only one possible spot left.
So R3C9 = 9.
Scan the empty cells in this row where 9 could go.
Across the whole row, 9 has only one possible spot left.
So R9C4 = 9.
Look at cell R3C2.
Every other digit already appears in its row, column or box.
Only one option remains: R3C2 = 7.
Look at cell R3C4.
Every other digit already appears in its row, column or box.
Only one option remains: R3C4 = 1.
Look at cell R4C4.
Every other digit already appears in its row, column or box.
Only one option remains: R4C4 = 2.
Look at cell R4C6.
Every other digit already appears in its row, column or box.
Only one option remains: R4C6 = 1.
Look at cell R1C4.
Every other digit already appears in its row, column or box.
Only one option remains: R1C4 = 4.
Look at cell R2C4.
Every other digit already appears in its row, column or box.
Only one option remains: R2C4 = 7.
Look at cell R2C6.
Every other digit already appears in its row, column or box.
Only one option remains: R2C6 = 2.
Look at cell R1C3.
Every other digit already appears in its row, column or box.
Only one option remains: R1C3 = 3.
Look at cell R2C2.
Every other digit already appears in its row, column or box.
Only one option remains: R2C2 = 4.
Look at cell R4C3.
Every other digit already appears in its row, column or box.
Only one option remains: R4C3 = 4.
Look at cell R4C5.
Every other digit already appears in its row, column or box.
Only one option remains: R4C5 = 7.
Look at cell R5C5.
Every other digit already appears in its row, column or box.
Only one option remains: R5C5 = 4.
Look at cell R5C7.
Every other digit already appears in its row, column or box.
Only one option remains: R5C7 = 7.
Look at cell R6C1.
Every other digit already appears in its row, column or box.
Only one option remains: R6C1 = 7.
Look at cell R6C9.
Every other digit already appears in its row, column or box.
Only one option remains: R6C9 = 4.
Look at cell R7C7.
Every other digit already appears in its row, column or box.
Only one option remains: R7C7 = 4.
Look at cell R9C9.
Every other digit already appears in its row, column or box.
Only one option remains: R9C9 = 7.
Look at cell R1C2.
Every other digit already appears in its row, column or box.
Only one option remains: R1C2 = 2.
Look at cell R4C1.
Every other digit already appears in its row, column or box.
Only one option remains: R4C1 = 3.
Look at cell R7C1.
Every other digit already appears in its row, column or box.
Only one option remains: R7C1 = 2.
Look at cell R7C2.
Every other digit already appears in its row, column or box.
Only one option remains: R7C2 = 6.
Look at cell R7C6.
Every other digit already appears in its row, column or box.
Only one option remains: R7C6 = 7.
Look at cell R8C1.
Every other digit already appears in its row, column or box.
Only one option remains: R8C1 = 4.
Look at cell R8C2.
Every other digit already appears in its row, column or box.
Only one option remains: R8C2 = 3.
Look at cell R8C6.
Every other digit already appears in its row, column or box.
Only one option remains: R8C6 = 6.
Look at cell R9C6.
Every other digit already appears in its row, column or box.
Only one option remains: R9C6 = 4.