Sudoku Solution No. 83

Hard Score 72 / 100
Digits appear one by one.

Step-by-step solution

Steps 63 Estimated time 104 – 156 min Hardest technique X-Wing Clues 23
Given digit (clue) Solved digit Placement (✓ RlCc=d) Elimination (✗ RlCc≠d)
1 Hidden Single ✓ R1C4=7
Scan the empty cells in this box where 7 could go. Across the whole box, 7 has only one possible spot left. So R1C4 = 7.
2 Hidden Single ✓ R3C9=7
Scan the empty cells in this row where 7 could go. Across the whole row, 7 has only one possible spot left. So R3C9 = 7.
3 Hidden Single ✓ R4C2=6
Scan the empty cells in this box where 6 could go. Across the whole box, 6 has only one possible spot left. So R4C2 = 6.
4 Hidden Single ✓ R5C2=7
Scan the empty cells in this column where 7 could go. Across the whole column, 7 has only one possible spot left. So R5C2 = 7.
5 Hidden Single ✓ R5C9=2
Scan the empty cells in this box where 2 could go. Across the whole box, 2 has only one possible spot left. So R5C9 = 2.
6 Hidden Single ✓ R6C5=7
Scan the empty cells in this box where 7 could go. Across the whole box, 7 has only one possible spot left. So R6C5 = 7.
7 Hidden Single ✓ R6C6=9
Scan the empty cells in this box where 9 could go. Across the whole box, 9 has only one possible spot left. So R6C6 = 9.
8 Hidden Single ✓ R8C6=8
Scan the empty cells in this column where 8 could go. Across the whole column, 8 has only one possible spot left. So R8C6 = 8.
9 Hidden Single ✓ R9C3=7
Scan the empty cells in this row where 7 could go. Across the whole row, 7 has only one possible spot left. So R9C3 = 7.
10 Hidden Single ✓ R1C1=2
Scan the empty cells in this box where 2 could go. Across the whole box, 2 has only one possible spot left. So R1C1 = 2.
11 Hidden Single ✓ R1C9=8
Scan the empty cells in this box where 8 could go. Across the whole box, 8 has only one possible spot left. So R1C9 = 8.
12 Hidden Single ✓ R2C3=8
Scan the empty cells in this box where 8 could go. Across the whole box, 8 has only one possible spot left. So R2C3 = 8.
13 Hidden Single ✓ R3C1=9
Scan the empty cells in this row where 9 could go. Across the whole row, 9 has only one possible spot left. So R3C1 = 9.
14 Hidden Single ✓ R3C6=2
Scan the empty cells in this box where 2 could go. Across the whole box, 2 has only one possible spot left. So R3C6 = 2.
15 Hidden Single ✓ R4C4=2
Scan the empty cells in this box where 2 could go. Across the whole box, 2 has only one possible spot left. So R4C4 = 2.
16 Hidden Single ✓ R4C6=4
Scan the empty cells in this box where 4 could go. Across the whole box, 4 has only one possible spot left. So R4C6 = 4.
17 Hidden Single ✓ R5C6=6
Scan the empty cells in this column where 6 could go. Across the whole column, 6 has only one possible spot left. So R5C6 = 6.
18 Hidden Single ✓ R6C1=4
Scan the empty cells in this row where 4 could go. Across the whole row, 4 has only one possible spot left. So R6C1 = 4.
19 Naked Single ✓ R1C5=1
Look at cell R1C5. Every other digit already appears in its row, column or box. Only one option remains: R1C5 = 1.
20 Naked Single ✓ R1C6=5
Look at cell R1C6. Every other digit already appears in its row, column or box. Only one option remains: R1C6 = 5.
21 Naked Single ✓ R2C6=3
Look at cell R2C6. Every other digit already appears in its row, column or box. Only one option remains: R2C6 = 3.
22 Naked Single ✓ R5C5=3
Look at cell R5C5. Every other digit already appears in its row, column or box. Only one option remains: R5C5 = 3.
23 Naked Single ✓ R9C6=1
Look at cell R9C6. Every other digit already appears in its row, column or box. Only one option remains: R9C6 = 1.
24 Naked Single ✓ R5C4=1
Look at cell R5C4. Every other digit already appears in its row, column or box. Only one option remains: R5C4 = 1.
25 Hidden Single ✓ R3C8=4
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.
26 Hidden Single ✓ R4C3=3
Scan the empty cells in this row where 3 could go. Across the whole row, 3 has only one possible spot left. So R4C3 = 3.
27 Hidden Single ✓ R7C7=8
Scan the empty cells in this column where 8 could go. Across the whole column, 8 has only one possible spot left. So R7C7 = 8.
28 Hidden Single ✓ R9C7=2
Scan the empty cells in this box where 2 could go. Across the whole box, 2 has only one possible spot left. So R9C7 = 2.
29 Hidden Single ✓ R2C7=6
Scan the empty cells in this box where 6 could go. Across the whole box, 6 has only one possible spot left. So R2C7 = 6.
30 Hidden Single ✓ R6C7=3
Scan the empty cells in this column where 3 could go. Across the whole column, 3 has only one possible spot left. So R6C7 = 3.
31 Hidden Single ✓ R7C5=2
Scan the empty cells in this row where 2 could go. Across the whole row, 2 has only one possible spot left. So R7C5 = 2.
32 Hidden Single ✓ R8C5=6
Scan the empty cells in this box where 6 could go. Across the whole box, 6 has only one possible spot left. So R8C5 = 6.
33 Two-String Kite ✗ 1 elimination
Find 1 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 1. R6C9 is seen by both free ends: 1 is therefore eliminated there.
34 Pointing ✗ 1 elimination
Look at where 1 can go in this box. All its spots lie on a single column (R4C8 and R6C8). 1 is therefore removed from that column outside the box.
35 Two-String Kite ✗ 1 elimination
Find 1 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 1. R8C2 is seen by both free ends: 1 is therefore eliminated there.
36 Pointing ✗ 1 elimination
Look at where 1 can go in this box. All its spots lie on a single row (R7C1 and R7C2). 1 is therefore removed from that row outside the box.
37 Two-String Kite ✗ 1 elimination
Find 5 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 5. R6C9 is seen by both free ends: 5 is therefore eliminated there.
38 Naked Single ✓ R6C9=6
Look at cell R6C9. Every other digit already appears in its row, column or box. Only one option remains: R6C9 = 6.
39 Hidden Single ✓ R7C8=6
Scan the empty cells in this row where 6 could go. Across the whole row, 6 has only one possible spot left. So R7C8 = 6.
40 Hidden Single ✓ R9C8=9
Scan the empty cells in this box where 9 could go. Across the whole box, 9 has only one possible spot left. So R9C8 = 9.
41 Naked Single ✓ R9C5=4
Look at cell R9C5. Every other digit already appears in its row, column or box. Only one option remains: R9C5 = 4.
42 Naked Single ✓ R2C5=9
Look at cell R2C5. Every other digit already appears in its row, column or box. Only one option remains: R2C5 = 9.
43 Naked Single ✓ R2C4=4
Look at cell R2C4. Every other digit already appears in its row, column or box. Only one option remains: R2C4 = 4.
44 Hidden Single ✓ R2C2=5
Scan the empty cells in this box where 5 could go. Across the whole box, 5 has only one possible spot left. So R2C2 = 5.
45 Hidden Single ✓ R2C9=1
Scan the empty cells in this box where 1 could go. Across the whole box, 1 has only one possible spot left. So R2C9 = 1.
46 Hidden Single ✓ R3C3=1
Scan the empty cells in this box where 1 could go. Across the whole box, 1 has only one possible spot left. So R3C3 = 1.
47 Hidden Single ✓ R3C7=5
Scan the empty cells in this box where 5 could go. Across the whole box, 5 has only one possible spot left. So R3C7 = 5.
48 Hidden Single ✓ R4C1=1
Scan the empty cells in this box where 1 could go. Across the whole box, 1 has only one possible spot left. So R4C1 = 1.
49 Hidden Single ✓ R4C8=8
Scan the empty cells in this box where 8 could go. Across the whole box, 8 has only one possible spot left. So R4C8 = 8.
50 Hidden Single ✓ R5C1=8
Scan the empty cells in this box where 8 could go. Across the whole box, 8 has only one possible spot left. So R5C1 = 8.
51 Hidden Single ✓ R5C8=5
Scan the empty cells in this box where 5 could go. Across the whole box, 5 has only one possible spot left. So R5C8 = 5.
52 Hidden Single ✓ R6C8=1
Scan the empty cells in this box where 1 could go. Across the whole box, 1 has only one possible spot left. So R6C8 = 1.
53 Hidden Single ✓ R7C1=5
Scan the empty cells in this box where 5 could go. Across the whole box, 5 has only one possible spot left. So R7C1 = 5.
54 Hidden Single ✓ R7C2=1
Scan the empty cells in this box where 1 could go. Across the whole box, 1 has only one possible spot left. So R7C2 = 1.
55 Hidden Single ✓ R7C4=9
Scan the empty cells in this box where 9 could go. Across the whole box, 9 has only one possible spot left. So R7C4 = 9.
56 Hidden Single ✓ R8C2=9
Scan the empty cells in this box where 9 could go. Across the whole box, 9 has only one possible spot left. So R8C2 = 9.
57 Hidden Single ✓ R8C7=1
Scan the empty cells in this box where 1 could go. Across the whole box, 1 has only one possible spot left. So R8C7 = 1.
58 Hidden Single ✓ R8C9=4
Scan the empty cells in this row where 4 could go. Across the whole row, 4 has only one possible spot left. So R8C9 = 4.
59 Hidden Single ✓ R9C9=5
Scan the empty cells in this box where 5 could go. Across the whole box, 5 has only one possible spot left. So R9C9 = 5.
60 Naked Single ✓ R6C3=5
Look at cell R6C3. Every other digit already appears in its row, column or box. Only one option remains: R6C3 = 5.
61 Naked Single ✓ R7C9=3
Look at cell R7C9. Every other digit already appears in its row, column or box. Only one option remains: R7C9 = 3.
62 Naked Single ✓ R8C4=5
Look at cell R8C4. Every other digit already appears in its row, column or box. Only one option remains: R8C4 = 5.
63 Naked Single ✓ R9C4=3
Look at cell R9C4. Every other digit already appears in its row, column or box. Only one option remains: R9C4 = 3.