Step-by-step solution
Steps 66
Estimated time 108 – 162 min
Hardest technique X-Wing
Clues 24
Given digit (clue)
Solved digit
Placement (✓ RlCc=d)
Elimination (✗ RlCc≠d)
Scan the empty cells in this box where 6 could go.
Across the whole box, 6 has only one possible spot left.
So R2C8 = 6.
Scan the empty cells in this box where 2 could go.
Across the whole box, 2 has only one possible spot left.
So R3C1 = 2.
Scan the empty cells in this row where 1 could go.
Across the whole row, 1 has only one possible spot left.
So R3C4 = 1.
Scan the empty cells in this row where 9 could go.
Across the whole row, 9 has only one possible spot left.
So R3C6 = 9.
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 box where 9 could go.
Across the whole box, 9 has only one possible spot left.
So R4C5 = 9.
Scan the empty cells in this box where 7 could go.
Across the whole box, 7 has only one possible spot left.
So R5C2 = 7.
Scan the empty cells in this box where 1 could go.
Across the whole box, 1 has only one possible spot left.
So R5C5 = 1.
Scan the empty cells in this box where 9 could go.
Across the whole box, 9 has only one possible spot left.
So R6C2 = 9.
Scan the empty cells in this box where 4 could go.
Across the whole box, 4 has only one possible spot left.
So R6C3 = 4.
Scan the empty cells in this column where 1 could go.
Across the whole column, 1 has only one possible spot left.
So R6C8 = 1.
Scan the empty cells in this box where 9 could go.
Across the whole box, 9 has only one possible spot left.
So R7C7 = 9.
Scan the empty cells in this box where 1 could go.
Across the whole box, 1 has only one possible spot left.
So R7C9 = 1.
Scan the empty cells in this row where 1 could go.
Across the whole row, 1 has only one possible spot left.
So R8C3 = 1.
Scan the empty cells in this row where 7 could go.
Across the whole row, 7 has only one possible spot left.
So R8C6 = 7.
Scan the empty cells in this column where 9 could go.
Across the whole column, 9 has only one possible spot left.
So R9C1 = 9.
Scan the empty cells in this box where 7 could go.
Across the whole box, 7 has only one possible spot left.
So R9C8 = 7.
Scan the empty cells in this row where 4 could go.
Across the whole row, 4 has only one possible spot left.
So R3C9 = 4.
Spot R9C7 and R9C9 on this row.
These two cells can only hold 3 and 5: they reserve those digits.
3 and 5 are therefore removed from the other cells of the row.
Look at cell R9C3.
Every other digit already appears in its row, column or box.
Only one option remains: R9C3 = 6.
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.
(1) Find where 2 and 4 can go on this column. (2) Find where 2 and 4 can go in this box.
(1) These two digits only fit in R7C2 and R9C2 on the column. (2) These two digits only fit in R7C2 and R9C2 in the box.
(1) The other candidates in R7C2 and R9C2 are therefore eliminated. (2) The other candidates in R7C2 and R9C2 are therefore eliminated.
Look at where 3 can go in this box.
All its spots lie on a single column (R1C2 and R2C2).
3 is therefore removed from that column outside the box.
Find 8 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 8.
R4C6 is seen by both free ends: 8 is therefore eliminated there.
Spot R4C6 and R4C8 on this row.
These two cells can only hold 2 and 5: they reserve those digits.
2 and 5 are therefore removed from the other cells of the row.
Find where 2 and 7 can go on this column.
These two digits only fit in R2C9 and R6C9 on the column.
The other candidates in R2C9 and R6C9 are therefore eliminated.
Look at where 8 can go in this box.
All its spots lie on a single column (R2C7 and R3C7).
8 is therefore removed from that column outside the box.
Scan the empty cells in this box where 8 could go.
Across the whole box, 8 has only one possible spot left.
So R1C2 = 8.
Scan the empty cells in this box where 8 could go.
Across the whole box, 8 has only one possible spot left.
So R2C4 = 8.
Scan the empty cells in this box where 8 could go.
Across the whole box, 8 has only one possible spot left.
So R3C7 = 8.
Scan the empty cells in this row where 8 could go.
Across the whole row, 8 has only one possible spot left.
So R6C6 = 8.
Scan the empty cells in this box where 8 could go.
Across the whole box, 8 has only one possible spot left.
So R8C1 = 8.
Look at cell R3C3.
Every other digit already appears in its row, column or box.
Only one option remains: R3C3 = 5.
Look at cell R5C1.
Every other digit already appears in its row, column or box.
Only one option remains: R5C1 = 3.
Look at cell R7C3.
Every other digit already appears in its row, column or box.
Only one option remains: R7C3 = 3.
Look at cell R8C2.
Every other digit already appears in its row, column or box.
Only one option remains: R8C2 = 5.
Look at cell R8C5.
Every other digit already appears in its row, column or box.
Only one option remains: R8C5 = 3.
Look at cell R2C2.
Every other digit already appears in its row, column or box.
Only one option remains: R2C2 = 3.
Look at cell R4C3.
Every other digit already appears in its row, column or box.
Only one option remains: R4C3 = 8.
Look at cell R4C9.
Every other digit already appears in its row, column or box.
Only one option remains: R4C9 = 3.
Look at cell R9C9.
Every other digit already appears in its row, column or box.
Only one option remains: R9C9 = 5.
Look at cell R5C9.
Every other digit already appears in its row, column or box.
Only one option remains: R5C9 = 8.
Look at cell R9C7.
Every other digit already appears in its row, column or box.
Only one option remains: R9C7 = 3.
Scan the empty cells in this row where 3 could go.
Across the whole row, 3 has only one possible spot left.
So R1C6 = 3.
Look at where 2 can go on this column.
All its spots lie within a single box (R7C4 and R9C4).
2 is therefore removed from the rest of the box.
Find 2 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 2.
R2C6 and R6C5 is seen by both free ends: 2 is therefore eliminated there.
Look at cell R6C5.
Every other digit already appears in its row, column or box.
Only one option remains: R6C5 = 6.
Look at cell R6C7.
Every other digit already appears in its row, column or box.
Only one option remains: R6C7 = 7.
Look at cell R6C9.
Every other digit already appears in its row, column or box.
Only one option remains: R6C9 = 2.
Look at cell R2C7.
Every other digit already appears in its row, column or box.
Only one option remains: R2C7 = 5.
Look at cell R2C9.
Every other digit already appears in its row, column or box.
Only one option remains: R2C9 = 7.
Look at cell R4C8.
Every other digit already appears in its row, column or box.
Only one option remains: R4C8 = 5.
Look at cell R5C7.
Every other digit already appears in its row, column or box.
Only one option remains: R5C7 = 6.
Look at cell R1C8.
Every other digit already appears in its row, column or box.
Only one option remains: R1C8 = 2.
Look at cell R2C6.
Every other digit already appears in its row, column or box.
Only one option remains: R2C6 = 4.
Look at cell R4C6.
Every other digit already appears in its row, column or box.
Only one option remains: R4C6 = 2.
Look at cell R5C6.
Every other digit already appears in its row, column or box.
Only one option remains: R5C6 = 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 R1C5.
Every other digit already appears in its row, column or box.
Only one option remains: R1C5 = 5.
Look at cell R2C5.
Every other digit already appears in its row, column or box.
Only one option remains: R2C5 = 2.
Look at cell R5C4.
Every other digit already appears in its row, column or box.
Only one option remains: R5C4 = 4.
Look at cell R7C5.
Every other digit already appears in its row, column or box.
Only one option remains: R7C5 = 4.
Look at cell R9C4.
Every other digit already appears in its row, column or box.
Only one option remains: R9C4 = 2.
Look at cell R7C2.
Every other digit already appears in its row, column or box.
Only one option remains: R7C2 = 2.
Look at cell R7C4.
Every other digit already appears in its row, column or box.
Only one option remains: R7C4 = 5.
Look at cell R9C2.
Every other digit already appears in its row, column or box.
Only one option remains: R9C2 = 4.