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)
Look at cell R2C2.
Every other digit already appears in its row, column or box.
Only one option remains: R2C2 = 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 R5C2.
Every other digit already appears in its row, column or box.
Only one option remains: R5C2 = 4.
Look at cell R5C1.
Every other digit already appears in its row, column or box.
Only one option remains: R5C1 = 5.
Scan the empty cells in this column where 5 could go.
Across the whole column, 5 has only one possible spot left.
So R1C8 = 5.
Scan the empty cells in this box where 6 could go.
Across the whole box, 6 has only one possible spot left.
So R4C4 = 6.
Scan the empty cells in this row where 5 could go.
Across the whole row, 5 has only one possible spot left.
So R4C6 = 5.
Scan the empty cells in this box where 3 could go.
Across the whole box, 3 has only one possible spot left.
So R4C9 = 3.
Scan the empty cells in this row where 9 could go.
Across the whole row, 9 has only one possible spot left.
So R6C3 = 9.
Scan the empty cells in this box where 3 could go.
Across the whole box, 3 has only one possible spot left.
So R6C6 = 3.
Scan the empty cells in this box where 7 could go.
Across the whole box, 7 has only one possible spot left.
So R7C3 = 7.
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 row where 5 could go.
Across the whole row, 5 has only one possible spot left.
So R8C9 = 5.
Look at cell R4C1.
Every other digit already appears in its row, column or box.
Only one option remains: R4C1 = 7.
Look at cell R6C1.
Every other digit already appears in its row, column or box.
Only one option remains: R6C1 = 6.
Scan the empty cells in this box where 6 could go.
Across the whole box, 6 has only one possible spot left.
So R1C6 = 6.
Scan the empty cells in this column where 7 could go.
Across the whole column, 7 has only one possible spot left.
So R1C7 = 7.
Scan the empty cells in this box where 7 could go.
Across the whole box, 7 has only one possible spot left.
So R2C6 = 7.
Scan the empty cells in this column where 6 could go.
Across the whole column, 6 has only one possible spot left.
So R3C3 = 6.
Scan the empty cells in this row where 7 could go.
Across the whole row, 7 has only one possible spot left.
So R6C9 = 7.
Scan the empty cells in this box where 6 could go.
Across the whole box, 6 has only one possible spot left.
So R7C2 = 6.
Scan the empty cells in this box where 7 could go.
Across the whole box, 7 has only one possible spot left.
So R9C4 = 7.
Scan the empty cells in this row where 6 could go.
Across the whole row, 6 has only one possible spot left.
So R9C9 = 6.
Look at cell R1C2.
Every other digit already appears in its row, column or box.
Only one option remains: R1C2 = 3.
Look at cell R8C2.
Every other digit already appears in its row, column or box.
Only one option remains: R8C2 = 1.
Scan the empty cells in this row where 3 could go.
Across the whole row, 3 has only one possible spot left.
So R8C1 = 3.
Spot R1C1 and R1C4 on this row.
These two cells can only hold 2 and 8: they reserve those digits.
2 and 8 are therefore removed from the other cells of the row.
(1) Look at where 1 can go in this box. (2) Look at where 9 can go in this box. (3) Look at where 4 can go in this box.
(1) All its spots lie on a single column (R1C5 and R2C5). (2) All its spots lie on a single column (R1C9 and R3C9). (3) All its spots lie on a single column (R4C5 and R6C5).
(1) 1 is therefore removed from that column outside the box. (2) 9 is therefore removed from that column outside the box. (3) 4 is therefore removed from that column outside the box.
Look at where 4 can go in this box.
All its spots lie on a single row (R3C4 and R3C6).
4 is therefore removed from that row outside the box.
Find 2 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 2.
R8C4 is seen by both free ends: 2 is therefore eliminated there.
Look at where 2 can go on this column.
All its spots lie within a single box (R1C4 and R3C4).
2 is therefore removed from the rest of 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.
R8C4 is seen by both free ends: 8 is therefore eliminated there.
Look at cell R8C4.
Every other digit already appears in its row, column or box.
Only one option remains: R8C4 = 4.
Scan the empty cells in this box where 9 could go.
Across the whole box, 9 has only one possible spot left.
So R1C5 = 9.
Scan the empty cells in this row where 4 could go.
Across the whole row, 4 has only one possible spot left.
So R3C6 = 4.
Scan the empty cells in this box where 9 could go.
Across the whole box, 9 has only one possible spot left.
So R3C9 = 9.
Look at cell R1C9.
Every other digit already appears in its row, column or box.
Only one option remains: R1C9 = 1.
Scan the empty cells in this row where 1 could go.
Across the whole row, 1 has only one possible spot left.
So R2C5 = 1.
Scan the empty cells in this row where 1 could go.
Across the whole row, 1 has only one possible spot left.
So R5C7 = 1.
Scan the empty cells in this box where 1 could go.
Across the whole box, 1 has only one possible spot left.
So R7C6 = 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 9 could go.
Across the whole box, 9 has only one possible spot left.
So R8C6 = 9.
Scan the empty cells in this column where 1 could go.
Across the whole column, 1 has only one possible spot left.
So R9C8 = 1.
(1) Look at where 8 can go on this column. (2) Look at where 2 can go on this column.
(1) All its spots lie within a single box (R8C7 and R9C7). (2) All its spots lie within a single box (R2C8 and R3C8).
(1) 8 is therefore removed from the rest of the box. (2) 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.
R5C6 and R4C7 is seen by both free ends: 2 is therefore eliminated there.
Look at cell R4C7.
Every other digit already appears in its row, column or box.
Only one option remains: R4C7 = 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 R5C9.
Every other digit already appears in its row, column or box.
Only one option remains: R5C9 = 2.
Look at cell R6C5.
Every other digit already appears in its row, column or box.
Only one option remains: R6C5 = 4.
Look at cell R6C8.
Every other digit already appears in its row, column or box.
Only one option remains: R6C8 = 8.
Look at cell R7C9.
Every other digit already appears in its row, column or box.
Only one option remains: R7C9 = 4.
Look at cell R9C6.
Every other digit already appears in its row, column or box.
Only one option remains: R9C6 = 2.
Look at cell R9C7.
Every other digit already appears in its row, column or box.
Only one option remains: R9C7 = 8.
Look at cell R2C9.
Every other digit already appears in its row, column or box.
Only one option remains: R2C9 = 8.
Look at cell R3C8.
Every other digit already appears in its row, column or box.
Only one option remains: R3C8 = 2.
Look at cell R4C5.
Every other digit already appears in its row, column or box.
Only one option remains: R4C5 = 2.
Look at cell R7C5.
Every other digit already appears in its row, column or box.
Only one option remains: R7C5 = 8.
Look at cell R8C7.
Every other digit already appears in its row, column or box.
Only one option remains: R8C7 = 2.
Look at cell R9C1.
Every other digit already appears in its row, column or box.
Only one option remains: R9C1 = 4.
Look at cell R2C3.
Every other digit already appears in its row, column or box.
Only one option remains: R2C3 = 2.
Look at cell R2C8.
Every other digit already appears in its row, column or box.
Only one option remains: R2C8 = 4.
Look at cell R3C4.
Every other digit already appears in its row, column or box.
Only one option remains: R3C4 = 8.
Look at cell R7C1.
Every other digit already appears in its row, column or box.
Only one option remains: R7C1 = 2.
Look at cell R8C3.
Every other digit already appears in its row, column or box.
Only one option remains: R8C3 = 8.
Look at cell R1C1.
Every other digit already appears in its row, column or box.
Only one option remains: R1C1 = 8.
Look at cell R1C4.
Every other digit already appears in its row, column or box.
Only one option remains: R1C4 = 2.