Step-by-step solution
Steps 66
Estimated time 108 – 162 min
Hardest technique X-Wing
Clues 23
Given digit (clue)
Solved digit
Placement (✓ RlCc=d)
Elimination (✗ RlCc≠d)
Scan the empty cells in this box where 9 could go.
Across the whole box, 9 has only one possible spot left.
So R1C4 = 9.
Scan the empty cells in this column where 2 could go.
Across the whole column, 2 has only one possible spot left.
So R3C6 = 2.
Scan the empty cells in this row where 4 could go.
Across the whole row, 4 has only one possible spot left.
So R3C8 = 4.
Scan the empty cells in this box where 4 could go.
Across the whole box, 4 has only one possible spot left.
So R4C4 = 4.
Scan the empty cells in this box where 4 could go.
Across the whole box, 4 has only one possible spot left.
So R5C2 = 4.
Scan the empty cells in this row where 8 could go.
Across the whole row, 8 has only one possible spot left.
So R6C5 = 8.
Scan the empty cells in this column where 4 could go.
Across the whole column, 4 has only one possible spot left.
So R6C9 = 4.
Scan the empty cells in this column where 9 could go.
Across the whole column, 9 has only one possible spot left.
So R7C6 = 9.
Scan the empty cells in this box where 5 could go.
Across the whole box, 5 has only one possible spot left.
So R7C8 = 5.
Scan the empty cells in this box where 9 could go.
Across the whole box, 9 has only one possible spot left.
So R8C1 = 9.
Scan the empty cells in this box where 5 could go.
Across the whole box, 5 has only one possible spot left.
So R8C4 = 5.
Scan the empty cells in this box where 7 could go.
Across the whole box, 7 has only one possible spot left.
So R8C5 = 7.
Scan the empty cells in this box where 4 could go.
Across the whole box, 4 has only one possible spot left.
So R9C5 = 4.
Scan the empty cells in this column where 9 could go.
Across the whole column, 9 has only one possible spot left.
So R2C7 = 9.
Scan the empty cells in this box where 7 could go.
Across the whole box, 7 has only one possible spot left.
So R2C8 = 7.
Scan the empty cells in this box where 1 could go.
Across the whole box, 1 has only one possible spot left.
So R3C4 = 1.
Scan the empty cells in this column where 5 could go.
Across the whole column, 5 has only one possible spot left.
So R5C7 = 5.
Scan the empty cells in this box where 7 could go.
Across the whole box, 7 has only one possible spot left.
So R9C7 = 7.
Scan the empty cells in this box where 8 could go.
Across the whole box, 8 has only one possible spot left.
So R9C8 = 8.
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 row where 1 could go.
Across the whole row, 1 has only one possible spot left.
So R9C3 = 1.
Spot R4C1 and R5C3 in this box.
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 box.
(1) Spot R4C3 and R6C3 on this column. (2) Spot R4C3 and R6C3 in this box.
(1) These two cells can only hold 5 and 9: they reserve those digits. (2) These two cells can only hold 5 and 9: they reserve those digits.
(1) 5 and 9 are therefore removed from the other cells of the column. (2) 5 and 9 are therefore removed from the other cells of the box.
Scan the empty cells in this row where 5 could go.
Across the whole row, 5 has only one possible spot left.
So R1C2 = 5.
Find where 1 and 6 can go on this column.
These two digits only fit in R1C8 and R8C8 on the column.
The other candidates in R1C8 and R8C8 are therefore eliminated.
Look at where 1 can go in this box.
All its spots lie on a single row (R2C1 and R2C2).
1 is therefore removed from that row outside the box.
Spot R2C9 and R7C9 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.
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.
R2C2 is seen by both free ends: 3 is therefore eliminated there.
Look at where 3 can go on this column.
All its spots lie within a single box (R7C2 and R8C2).
3 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.
R2C2 is seen by both free ends: 6 is therefore eliminated there.
Look at cell R2C2.
Every other digit already appears in its row, column or box.
Only one option remains: R2C2 = 1.
Look at cell R6C2.
Every other digit already appears in its row, column or box.
Only one option remains: R6C2 = 7.
Look at cell R6C4.
Every other digit already appears in its row, column or box.
Only one option remains: R6C4 = 3.
Look at cell R9C4.
Every other digit already appears in its row, column or box.
Only one option remains: R9C4 = 6.
Look at cell R9C6.
Every other digit already appears in its row, column or box.
Only one option remains: R9C6 = 3.
Look at cell R5C4.
Every other digit already appears in its row, column or box.
Only one option remains: R5C4 = 7.
Scan the empty cells in this box where 8 could go.
Across the whole box, 8 has only one possible spot left.
So R1C7 = 8.
Scan the empty cells in this box where 2 could go.
Across the whole box, 2 has only one possible spot left.
So R1C9 = 2.
Scan the empty cells in this box where 8 could go.
Across the whole box, 8 has only one possible spot left.
So R3C1 = 8.
Scan the empty cells in this row where 7 could go.
Across the whole row, 7 has only one possible spot left.
So R7C1 = 7.
Scan the empty cells in this box where 8 could go.
Across the whole box, 8 has only one possible spot left.
So R7C3 = 8.
Scan the empty cells in this box where 3 could go.
Across the whole box, 3 has only one possible spot left.
So R7C9 = 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 6 could go.
Across the whole box, 6 has only one possible spot left.
So R8C8 = 6.
Look at cell R1C8.
Every other digit already appears in its row, column or box.
Only one option remains: R1C8 = 1.
Look at cell R2C9.
Every other digit already appears in its row, column or box.
Only one option remains: R2C9 = 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 R7C2.
Every other digit already appears in its row, column or box.
Only one option remains: R7C2 = 6.
Look at cell R8C2.
Every other digit already appears in its row, column or box.
Only one option remains: R8C2 = 3.
Look at cell R8C9.
Every other digit already appears in its row, column or box.
Only one option remains: R8C9 = 1.
Look at cell R2C1.
Every other digit already appears in its row, column or box.
Only one option remains: R2C1 = 3.
Look at cell R3C5.
Every other digit already appears in its row, column or box.
Only one option remains: R3C5 = 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 = 5.
Look at cell R5C3.
Every other digit already appears in its row, column or box.
Only one option remains: R5C3 = 3.
Look at cell R5C8.
Every other digit already appears in its row, column or box.
Only one option remains: R5C8 = 2.
Look at cell R6C6.
Every other digit already appears in its row, column or box.
Only one option remains: R6C6 = 1.
Look at cell R6C8.
Every other digit already appears in its row, column or box.
Only one option remains: R6C8 = 9.
Look at cell R1C3.
Every other digit already appears in its row, column or box.
Only one option remains: R1C3 = 6.
Look at cell R1C5.
Every other digit already appears in its row, column or box.
Only one option remains: R1C5 = 3.
Look at cell R4C3.
Every other digit already appears in its row, column or box.
Only one option remains: R4C3 = 9.
Look at cell R4C8.
Every other digit already appears in its row, column or box.
Only one option remains: R4C8 = 3.
Look at cell R5C1.
Every other digit already appears in its row, column or box.
Only one option remains: R5C1 = 1.
Look at cell R5C6.
Every other digit already appears in its row, column or box.
Only one option remains: R5C6 = 6.
Look at cell R6C1.
Every other digit already appears in its row, column or box.
Only one option remains: R6C1 = 2.
Look at cell R6C3.
Every other digit already appears in its row, column or box.
Only one option remains: R6C3 = 5.