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 box where 6 could go.
Across the whole box, 6 has only one possible spot left.
So R1C3 = 6.
Scan the empty cells in this row where 5 could go.
Across the whole row, 5 has only one possible spot left.
So R1C4 = 5.
Scan the empty cells in this box where 3 could go.
Across the whole box, 3 has only one possible spot left.
So R1C9 = 3.
Scan the empty cells in this box where 3 could go.
Across the whole box, 3 has only one possible spot left.
So R3C1 = 3.
Scan the empty cells in this box where 5 could go.
Across the whole box, 5 has only one possible spot left.
So R4C1 = 5.
Scan the empty cells in this row where 3 could go.
Across the whole row, 3 has only one possible spot left.
So R5C4 = 3.
Scan the empty cells in this box where 5 could go.
Across the whole box, 5 has only one possible spot left.
So R5C9 = 5.
Scan the empty cells in this box where 5 could go.
Across the whole box, 5 has only one possible spot left.
So R7C2 = 5.
Scan the empty cells in this row where 4 could go.
Across the whole row, 4 has only one possible spot left.
So R7C9 = 4.
Scan the empty cells in this box where 5 could go.
Across the whole box, 5 has only one possible spot left.
So R8C8 = 5.
Scan the empty cells in this box where 3 could go.
Across the whole box, 3 has only one possible spot left.
So R9C3 = 3.
Scan the empty cells in this box where 6 could go.
Across the whole box, 6 has only one possible spot left.
So R9C9 = 6.
Scan the empty cells in this row where 1 could go.
Across the whole row, 1 has only one possible spot left.
So R1C7 = 1.
Scan the empty cells in this column where 6 could go.
Across the whole column, 6 has only one possible spot left.
So R2C5 = 6.
Scan the empty cells in this row where 6 could go.
Across the whole row, 6 has only one possible spot left.
So R4C7 = 6.
Scan the empty cells in this column where 6 could go.
Across the whole column, 6 has only one possible spot left.
So R5C2 = 6.
Scan the empty cells in this box where 1 could go.
Across the whole box, 1 has only one possible spot left.
So R6C9 = 1.
(1) Spot R8C6 and R8C7 on this row. (2) Spot R2C9 and R3C9 in this box.
(1) These two cells can only hold 7 and 9: they reserve those digits. (2) These two cells can only hold 2 and 9: they reserve those digits.
(1) 7 and 9 are therefore removed from the other cells of the row. (2) 2 and 9 are therefore removed from the other cells of the box.
Find where 2 and 9 can go on this row.
These two digits only fit in R2C4 and R2C9 on the row.
The other candidates in R2C4 and R2C9 are therefore eliminated.
Spot R2C4 and R4C4 on this column.
These two cells can only hold 2 and 9: they reserve those digits.
2 and 9 are therefore removed from the other cells of the column.
Look at cell R6C4.
Every other digit already appears in its row, column or box.
Only one option remains: R6C4 = 7.
(1) Find where 1 and 7 can go on this row. (2) Find where 1 and 7 can go in this box.
(1) These two digits only fit in R5C1 and R5C3 on the row. (2) These two digits only fit in R5C1 and R5C3 in the box.
(1) The other candidates in R5C1 and R5C3 are therefore eliminated. (2) The other candidates in R5C1 and R5C3 are therefore eliminated.
Scan the empty cells in this box where 4 could go.
Across the whole box, 4 has only one possible spot left.
So R2C1 = 4.
Scan the empty cells in this column where 2 could go.
Across the whole column, 2 has only one possible spot left.
So R6C1 = 2.
(1) Look at where 1 can go in this box. (2) Look at where 8 can go in this box. (3) Look at where 4 can go in this box. (4) Look at where 8 can go in this box.
(1) All its spots lie on a single row (R3C4 and R3C5). (2) All its spots lie on a single row (R6C2 and R6C3). (3) All its spots lie on a single row (R5C5 and R5C6). (4) All its spots lie on a single row (R7C4 and R7C6).
(1) 1 is therefore removed from that row outside the box. (2) 8 is therefore removed from that row outside the box. (3) 4 is therefore removed from that row outside the box. (4) 8 is therefore removed from that row outside the box.
Scan the empty cells in this column where 8 could go.
Across the whole column, 8 has only one possible spot left.
So R9C1 = 8.
Find 7 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 7.
R9C2 is seen by both free ends: 7 is therefore eliminated there.
Spot R9C2 and R9C5 on this row.
These two cells can only hold 1 and 9: they reserve those digits.
1 and 9 are therefore removed from the other cells of the row.
Look at cell R8C7.
Every other digit already appears in its row, column or box.
Only one option remains: R8C7 = 9.
Look at cell R6C7.
Every other digit already appears in its row, column or box.
Only one option remains: R6C7 = 4.
Look at cell R8C6.
Every other digit already appears in its row, column or box.
Only one option remains: R8C6 = 7.
Scan the empty cells in this column where 4 could go.
Across the whole column, 4 has only one possible spot left.
So R1C8 = 4.
Scan the empty cells in this row where 4 could go.
Across the whole row, 4 has only one possible spot left.
So R4C3 = 4.
Look at cell R1C6.
Every other digit already appears in its row, column or box.
Only one option remains: R1C6 = 8.
Look at cell R3C4.
Every other digit already appears in its row, column or box.
Only one option remains: R3C4 = 1.
Look at cell R7C6.
Every other digit already appears in its row, column or box.
Only one option remains: R7C6 = 9.
Look at cell R8C4.
Every other digit already appears in its row, column or box.
Only one option remains: R8C4 = 6.
Look at cell R9C5.
Every other digit already appears in its row, column or box.
Only one option remains: R9C5 = 1.
Look at cell R7C3.
Every other digit already appears in its row, column or box.
Only one option remains: R7C3 = 7.
Look at cell R7C4.
Every other digit already appears in its row, column or box.
Only one option remains: R7C4 = 8.
Look at cell R8C1.
Every other digit already appears in its row, column or box.
Only one option remains: R8C1 = 1.
Look at cell R9C2.
Every other digit already appears in its row, column or box.
Only one option remains: R9C2 = 9.
Look at cell R5C1.
Every other digit already appears in its row, column or box.
Only one option remains: R5C1 = 7.
Look at cell R5C3.
Every other digit already appears in its row, column or box.
Only one option remains: R5C3 = 1.
Look at cell R6C2.
Every other digit already appears in its row, column or box.
Only one option remains: R6C2 = 8.
Look at cell R6C3.
Every other digit already appears in its row, column or box.
Only one option remains: R6C3 = 9.
Look at cell R7C1.
Every other digit already appears in its row, column or box.
Only one option remains: R7C1 = 6.
Look at cell R2C3.
Every other digit already appears in its row, column or box.
Only one option remains: R2C3 = 8.
Look at cell R2C8.
Every other digit already appears in its row, column or box.
Only one option remains: R2C8 = 7.
Look at cell R3C2.
Every other digit already appears in its row, column or box.
Only one option remains: R3C2 = 7.
Look at cell R3C7.
Every other digit already appears in its row, column or box.
Only one option remains: R3C7 = 8.
Look at cell R5C7.
Every other digit already appears in its row, column or box.
Only one option remains: R5C7 = 2.
Look at cell R9C7.
Every other digit already appears in its row, column or box.
Only one option remains: R9C7 = 7.
Look at cell R9C8.
Every other digit already appears in its row, column or box.
Only one option remains: R9C8 = 2.
Look at cell R2C2.
Every other digit already appears in its row, column or box.
Only one option remains: R2C2 = 1.
Look at cell R4C8.
Every other digit already appears in its row, column or box.
Only one option remains: R4C8 = 9.
Look at cell R5C6.
Every other digit already appears in its row, column or box.
Only one option remains: R5C6 = 4.
Look at cell R5C8.
Every other digit already appears in its row, column or box.
Only one option remains: R5C8 = 8.
Look at cell R3C6.
Every other digit already appears in its row, column or box.
Only one option remains: R3C6 = 2.
Look at cell R3C9.
Every other digit already appears in its row, column or box.
Only one option remains: R3C9 = 9.
Look at cell R4C4.
Every other digit already appears in its row, column or box.
Only one option remains: R4C4 = 2.
Look at cell R5C5.
Every other digit already appears in its row, column or box.
Only one option remains: R5C5 = 9.
Look at cell R2C4.
Every other digit already appears in its row, column or box.
Only one option remains: R2C4 = 9.
Look at cell R2C9.
Every other digit already appears in its row, column or box.
Only one option remains: R2C9 = 2.
Look at cell R3C5.
Every other digit already appears in its row, column or box.
Only one option remains: R3C5 = 4.