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)
Scan the empty cells in this column where 5 could go.
Across the whole column, 5 has only one possible spot left.
So R1C7 = 5.
Scan the empty cells in this box where 9 could go.
Across the whole box, 9 has only one possible spot left.
So R1C8 = 9.
Scan the empty cells in this row where 5 could go.
Across the whole row, 5 has only one possible spot left.
So R2C6 = 5.
Scan the empty cells in this box where 4 could go.
Across the whole box, 4 has only one possible spot left.
So R2C8 = 4.
Scan the empty cells in this column where 9 could go.
Across the whole column, 9 has only one possible spot left.
So R3C2 = 9.
Scan the empty cells in this box where 6 could go.
Across the whole box, 6 has only one possible spot left.
So R3C4 = 6.
Scan the empty cells in this box where 4 could go.
Across the whole box, 4 has only one possible spot left.
So R3C6 = 4.
Scan the empty cells in this box where 7 could go.
Across the whole box, 7 has only one possible spot left.
So R4C3 = 7.
Scan the empty cells in this row where 4 could go.
Across the whole row, 4 has only one possible spot left.
So R6C9 = 4.
Scan the empty cells in this box where 6 could go.
Across the whole box, 6 has only one possible spot left.
So R7C8 = 6.
Scan the empty cells in this box where 9 could go.
Across the whole box, 9 has only one possible spot left.
So R7C9 = 9.
Scan the empty cells in this box where 5 could go.
Across the whole box, 5 has only one possible spot left.
So R8C1 = 5.
Scan the empty cells in this row where 4 could go.
Across the whole row, 4 has only one possible spot left.
So R8C2 = 4.
Scan the empty cells in this box where 2 could go.
Across the whole box, 2 has only one possible spot left.
So R8C3 = 2.
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 7 could go.
Across the whole column, 7 has only one possible spot left.
So R8C7 = 7.
Look at cell R7C3.
Every other digit already appears in its row, column or box.
Only one option remains: R7C3 = 8.
Look at cell R6C3.
Every other digit already appears in its row, column or box.
Only one option remains: R6C3 = 6.
Scan the empty cells in this box where 6 could go.
Across the whole box, 6 has only one possible spot left.
So R4C6 = 6.
Scan the empty cells in this box where 7 could go.
Across the whole box, 7 has only one possible spot left.
So R5C6 = 7.
Scan the empty cells in this box where 6 could go.
Across the whole box, 6 has only one possible spot left.
So R5C7 = 6.
Scan the empty cells in this box where 9 could go.
Across the whole box, 9 has only one possible spot left.
So R6C7 = 9.
Scan the empty cells in this column where 7 could go.
Across the whole column, 7 has only one possible spot left.
So R7C4 = 7.
Scan the empty cells in this box where 7 could go.
Across the whole box, 7 has only one possible spot left.
So R9C1 = 7.
Look at cell R4C7.
Every other digit already appears in its row, column or box.
Only one option remains: R4C7 = 1.
Scan the empty cells in this column where 6 could go.
Across the whole column, 6 has only one possible spot left.
So R2C1 = 6.
Scan the empty cells in this row where 9 could go.
Across the whole row, 9 has only one possible spot left.
So R5C5 = 9.
Scan the empty cells in this box where 1 could go.
Across the whole box, 1 has only one possible spot left.
So R7C1 = 1.
Scan the empty cells in this box where 3 could go.
Across the whole box, 3 has only one possible spot left.
So R7C2 = 3.
Scan the empty cells in this row where 6 could go.
Across the whole row, 6 has only one possible spot left.
So R9C2 = 6.
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 1 could go.
Across the whole row, 1 has only one possible spot left.
So R6C2 = 1.
Scan the empty cells in this box where 5 could go.
Across the whole box, 5 has only one possible spot left.
So R6C4 = 5.
(1) Look at where 1 can go in this box. (2) Look at where 3 can go in this box. (3) Look at where 1 can go in this box.
(1) All its spots lie on a single row (R3C8 and R3C9). (2) All its spots lie on a single row (R4C8 and R4C9). (3) All its spots lie on a single row (R9C5 and R9C6).
(1) 1 is therefore removed from that row outside the box. (2) 3 is therefore removed from that row outside the box. (3) 1 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.
R2C5 is seen by both free ends: 2 is therefore eliminated there.
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.
R3C8 and R4C9 is seen by both free ends: 2 is therefore eliminated there.
Look at cell R3C8.
Every other digit already appears in its row, column or box.
Only one option remains: R3C8 = 1.
Scan the empty cells in this row where 1 could go.
Across the whole row, 1 has only one possible spot left.
So R8C9 = 1.
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.
R1C1 is seen by both free ends: 2 is therefore eliminated there.
Look at where 2 can go on this row.
All its spots lie within a single box (R1C4 and R1C5).
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.
R6C5 is seen by both free ends: 8 is therefore eliminated there.
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.
R4C4 is seen by both free ends: 8 is therefore eliminated there.
Look at cell R4C4.
Every other digit already appears in its row, column or box.
Only one option remains: R4C4 = 2.
Look at cell R6C5.
Every other digit already appears in its row, column or box.
Only one option remains: R6C5 = 3.
Look at cell R6C6.
Every other digit already appears in its row, column or box.
Only one option remains: R6C6 = 8.
Look at cell R3C5.
Every other digit already appears in its row, column or box.
Only one option remains: R3C5 = 7.
Look at cell R3C9.
Every other digit already appears in its row, column or box.
Only one option remains: R3C9 = 2.
Look at cell R6C1.
Every other digit already appears in its row, column or box.
Only one option remains: R6C1 = 2.
Look at cell R2C5.
Every other digit already appears in its row, column or box.
Only one option remains: R2C5 = 8.
Look at cell R2C9.
Every other digit already appears in its row, column or box.
Only one option remains: R2C9 = 7.
Look at cell R3C1.
Every other digit already appears in its row, column or box.
Only one option remains: R3C1 = 3.
Look at cell R5C2.
Every other digit already appears in its row, column or box.
Only one option remains: R5C2 = 8.
Look at cell R5C8.
Every other digit already appears in its row, column or box.
Only one option remains: R5C8 = 2.
Look at cell R9C5.
Every other digit already appears in its row, column or box.
Only one option remains: R9C5 = 1.
Look at cell R9C6.
Every other digit already appears in its row, column or box.
Only one option remains: R9C6 = 3.
Look at cell R9C9.
Every other digit already appears in its row, column or box.
Only one option remains: R9C9 = 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 = 3.
Look at cell R1C5.
Every other digit already appears in its row, column or box.
Only one option remains: R1C5 = 2.
Look at cell R1C6.
Every other digit already appears in its row, column or box.
Only one option remains: R1C6 = 1.
Look at cell R2C2.
Every other digit already appears in its row, column or box.
Only one option remains: R2C2 = 2.
Look at cell R4C9.
Every other digit already appears in its row, column or box.
Only one option remains: R4C9 = 3.
Look at cell R8C4.
Every other digit already appears in its row, column or box.
Only one option remains: R8C4 = 8.
Look at cell R8C8.
Every other digit already appears in its row, column or box.
Only one option remains: R8C8 = 3.
Look at cell R4C8.
Every other digit already appears in its row, column or box.
Only one option remains: R4C8 = 8.