Step-by-step solution
Steps 63
Estimated time 104 – 156 min
Hardest technique X-Wing
Clues 22
Given digit (clue)
Solved digit
Placement (✓ RlCc=d)
Elimination (✗ RlCc≠d)
Look at cell R9C7.
Every other digit already appears in its row, column or box.
Only one option remains: R9C7 = 9.
Look at cell R9C5.
Every other digit already appears in its row, column or box.
Only one option remains: R9C5 = 6.
Scan the empty cells in this column where 6 could go.
Across the whole column, 6 has only one possible spot left.
So R2C4 = 6.
Scan the empty cells in this box where 3 could go.
Across the whole box, 3 has only one possible spot left.
So R2C5 = 3.
Scan the empty cells in this row where 9 could go.
Across the whole row, 9 has only one possible spot left.
So R3C8 = 9.
Scan the empty cells in this box where 3 could go.
Across the whole box, 3 has only one possible spot left.
So R7C8 = 3.
Scan the empty cells in this column where 4 could go.
Across the whole column, 4 has only one possible spot left.
So R8C6 = 4.
Scan the empty cells in this column where 7 could go.
Across the whole column, 7 has only one possible spot left.
So R2C8 = 7.
Scan the empty cells in this row where 7 could go.
Across the whole row, 7 has only one possible spot left.
So R3C1 = 7.
Scan the empty cells in this box where 7 could go.
Across the whole box, 7 has only one possible spot left.
So R4C2 = 7.
Scan the empty cells in this column where 2 could go.
Across the whole column, 2 has only one possible spot left.
So R5C5 = 2.
Scan the empty cells in this box where 9 could go.
Across the whole box, 9 has only one possible spot left.
So R5C6 = 9.
Scan the empty cells in this box where 7 could go.
Across the whole box, 7 has only one possible spot left.
So R6C4 = 7.
Scan the empty cells in this box where 9 could go.
Across the whole box, 9 has only one possible spot left.
So R6C9 = 9.
Scan the empty cells in this box where 7 could go.
Across the whole box, 7 has only one possible spot left.
So R7C6 = 7.
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 7 could go.
Across the whole box, 7 has only one possible spot left.
So R8C9 = 7.
Scan the empty cells in this box where 4 could go.
Across the whole box, 4 has only one possible spot left.
So R9C1 = 4.
Scan the empty cells in this box where 7 could go.
Across the whole box, 7 has only one possible spot left.
So R9C3 = 7.
Scan the empty cells in this column where 4 could go.
Across the whole column, 4 has only one possible spot left.
So R2C2 = 4.
Scan the empty cells in this box where 9 could go.
Across the whole box, 9 has only one possible spot left.
So R2C3 = 9.
Scan the empty cells in this row where 8 could go.
Across the whole row, 8 has only one possible spot left.
So R2C7 = 8.
Scan the empty cells in this row where 2 could go.
Across the whole row, 2 has only one possible spot left.
So R3C6 = 2.
Scan the empty cells in this column where 3 could go.
Across the whole column, 3 has only one possible spot left.
So R4C4 = 3.
Scan the empty cells in this box where 3 could go.
Across the whole box, 3 has only one possible spot left.
So R6C7 = 3.
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 row where 8 could go.
Across the whole row, 8 has only one possible spot left.
So R4C5 = 8.
(1) Find where 2 and 6 can go on this row. (2) Find where 2 and 6 can go in this box.
(1) These two digits only fit in R7C1 and R7C3 on the row. (2) These two digits only fit in R7C1 and R7C3 in the box.
(1) The other candidates in R7C1 and R7C3 are therefore eliminated. (2) The other candidates in R7C1 and R7C3 are therefore eliminated.
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.
R4C7 is seen by both free ends: 1 is therefore eliminated there.
Look at where 1 can go in this box.
All its spots lie on a single column (R4C9 and R5C9).
1 is therefore removed from that column outside the box.
Look at cell R2C9.
Every other digit already appears in its row, column or box.
Only one option remains: R2C9 = 2.
Find 5 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 5.
R4C7 is seen by both free ends: 5 is therefore eliminated there.
Look at cell R4C7.
Every other digit already appears in its row, column or box.
Only one option remains: R4C7 = 6.
Look at cell R5C9.
Every other digit already appears in its row, column or box.
Only one option remains: R5C9 = 1.
Look at cell R4C9.
Every other digit already appears in its row, column or box.
Only one option remains: R4C9 = 4.
Look at cell R5C2.
Every other digit already appears in its row, column or box.
Only one option remains: R5C2 = 5.
Look at cell R5C8.
Every other digit already appears in its row, column or box.
Only one option remains: R5C8 = 8.
Look at cell R6C8.
Every other digit already appears in its row, column or box.
Only one option remains: R6C8 = 5.
Look at cell R1C8.
Every other digit already appears in its row, column or box.
Only one option remains: R1C8 = 4.
Look at cell R1C9.
Every other digit already appears in its row, column or box.
Only one option remains: R1C9 = 6.
Look at cell R4C3.
Every other digit already appears in its row, column or box.
Only one option remains: R4C3 = 1.
Look at cell R4C6.
Every other digit already appears in its row, column or box.
Only one option remains: R4C6 = 5.
Look at cell R6C1.
Every other digit already appears in its row, column or box.
Only one option remains: R6C1 = 8.
Look at cell R6C3.
Every other digit already appears in its row, column or box.
Only one option remains: R6C3 = 4.
Look at cell R6C5.
Every other digit already appears in its row, column or box.
Only one option remains: R6C5 = 1.
Look at cell R2C6.
Every other digit already appears in its row, column or box.
Only one option remains: R2C6 = 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 R3C7.
Every other digit already appears in its row, column or box.
Only one option remains: R3C7 = 1.
Look at cell R7C4.
Every other digit already appears in its row, column or box.
Only one option remains: R7C4 = 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 R2C1.
Every other digit already appears in its row, column or box.
Only one option remains: R2C1 = 5.
Look at cell R7C2.
Every other digit already appears in its row, column or box.
Only one option remains: R7C2 = 9.
Look at cell R7C5.
Every other digit already appears in its row, column or box.
Only one option remains: R7C5 = 5.
Look at cell R8C2.
Every other digit already appears in its row, column or box.
Only one option remains: R8C2 = 1.
Look at cell R8C5.
Every other digit already appears in its row, column or box.
Only one option remains: R8C5 = 9.
Look at cell R1C3.
Every other digit already appears in its row, column or box.
Only one option remains: R1C3 = 2.
Look at cell R7C3.
Every other digit already appears in its row, column or box.
Only one option remains: R7C3 = 6.
Look at cell R8C1.
Every other digit already appears in its row, column or box.
Only one option remains: R8C1 = 3.
Look at cell R8C3.
Every other digit already appears in its row, column or box.
Only one option remains: R8C3 = 5.
Look at cell R1C1.
Every other digit already appears in its row, column or box.
Only one option remains: R1C1 = 1.
Look at cell R5C1.
Every other digit already appears in its row, column or box.
Only one option remains: R5C1 = 6.
Look at cell R5C3.
Every other digit already appears in its row, column or box.
Only one option remains: R5C3 = 3.
Look at cell R7C1.
Every other digit already appears in its row, column or box.
Only one option remains: R7C1 = 2.