Step 0

Starting puzzle

1 2 3 4 5 6 7 8 9
A 1       2     8  
B 6       4       9
C         7     4 6
D   2       4   5  
E     1       7    
F   9   6       2  
G 9 5     3        
H 2       9       8
I   7     6       5

Step 1

The number 6 does not yet appear in row A. Due to other 6s on the grid, the only place it can go is cell A6.

1 2 3 4 5 6 7 8 9
A 1       2 6   8  
B 6       4       9
C         7     4 6
D   2       4   5  
E     1       7    
F   9   6       2  
G 9 5     3        
H 2       9       8
I   7     6       5

Step 2

The number 1 does not yet appear in column 2. Due to other 1s on the grid, the only place it can go is cell H2.

1 2 3 4 5 6 7 8 9
A 1       2 6   8  
B 6       4       9
C         7     4 6
D   2       4   5  
E     1       7    
F   9   6       2  
G 9 5     3        
H 2 1     9       8
I   7     6       5

Step 3

The number 6 is missing from column 2 and its only possible position is cell E2.

1 2 3 4 5 6 7 8 9
A 1       2 6   8  
B 6       4       9
C         7     4 6
D   2       4   5  
E   6 1       7    
F   9   6       2  
G 9 5     3        
H 2 1     9       8
I   7     6       5

Step 4

Because of the number 6 just placed, the only position in row D for another 6 is cell D7.

1 2 3 4 5 6 7 8 9
A 1       2 6   8  
B 6       4       9
C         7     4 6
D   2       4 6 5  
E   6 1       7    
F   9   6       2  
G 9 5     3        
H 2 1     9       8
I   7     6       5

Step 5

The number 8 does not yet appear in column 7. Due to other 8s on the grid, the only place it can go is cell F7.

1 2 3 4 5 6 7 8 9
A 1       2 6   8  
B 6       4       9
C         7     4 6
D   2       4 6 5  
E   6 1       7    
F   9   6     8 2  
G 9 5     3        
H 2 1     9       8
I   7     6       5

Step 6

The number 4 is missing from column 2 and its only possible position is cell A2.

1 2 3 4 5 6 7 8 9
A 1 4     2 6   8  
B 6       4       9
C         7     4 6
D   2       4 6 5  
E   6 1       7    
F   9   6     8 2  
G 9 5     3        
H 2 1     9       8
I   7     6       5

Step 7

The number 9 is missing from box D7-F9 and its only possible position is cell E8.

1 2 3 4 5 6 7 8 9
A 1 4     2 6   8  
B 6       4       9
C         7     4 6
D   2       4 6 5  
E   6 1       7 9  
F   9   6     8 2  
G 9 5     3        
H 2 1     9       8
I   7     6       5

Step 8

Because of the number 9 just placed, the only position in row D for another 9 is cell D4.

1 2 3 4 5 6 7 8 9
A 1 4     2 6   8  
B 6       4       9
C         7     4 6
D   2   9   4 6 5  
E   6 1       7 9  
F   9   6     8 2  
G 9 5     3        
H 2 1     9       8
I   7     6       5

Step 9

Because of the number 9 just placed, the only position in column 6 for another 9 is cell C6.

1 2 3 4 5 6 7 8 9
A 1 4     2 6   8  
B 6       4       9
C         7 9   4 6
D   2   9   4 6 5  
E   6 1       7 9  
F   9   6     8 2  
G 9 5     3        
H 2 1     9       8
I   7     6       5

Step 10

Because of the number 9 just placed, the only position in row A for another 9 is cell A3.

1 2 3 4 5 6 7 8 9
A 1 4 9   2 6   8  
B 6       4       9
C         7 9   4 6
D   2   9   4 6 5  
E   6 1       7 9  
F   9   6     8 2  
G 9 5     3        
H 2 1     9       8
I   7     6       5

Step 11

Because of the number 9 just placed, the only position in column 7 for another 9 is cell I7.

1 2 3 4 5 6 7 8 9
A 1 4 9   2 6   8  
B 6       4       9
C         7 9   4 6
D   2   9   4 6 5  
E   6 1       7 9  
F   9   6     8 2  
G 9 5     3        
H 2 1     9       8
I   7     6   9   5

Step 12

The number 7 is missing from row A and its only possible position is cell A9.

1 2 3 4 5 6 7 8 9
A 1 4 9   2 6   8 7
B 6       4       9
C         7 9   4 6
D   2   9   4 6 5  
E   6 1       7 9  
F   9   6     8 2  
G 9 5     3        
H 2 1     9       8
I   7     6   9   5

Step 13

Because of the number 7 just placed, the only position in row B for another 7 is cell B3.

1 2 3 4 5 6 7 8 9
A 1 4 9   2 6   8 7
B 6   7   4       9
C         7 9   4 6
D   2   9   4 6 5  
E   6 1       7 9  
F   9   6     8 2  
G 9 5     3        
H 2 1     9       8
I   7     6   9   5

Step 14

The number 2 does not yet appear in column 3. Due to other 2s on the grid, the only place it can go is cell C3.

1 2 3 4 5 6 7 8 9
A 1 4 9   2 6   8 7
B 6   7   4       9
C     2   7 9   4 6
D   2   9   4 6 5  
E   6 1       7 9  
F   9   6     8 2  
G 9 5     3        
H 2 1     9       8
I   7     6   9   5

Step 15

Because of the number 2 just placed, the only position in row B for another 2 is cell B7.

1 2 3 4 5 6 7 8 9
A 1 4 9   2 6   8 7
B 6   7   4   2   9
C     2   7 9   4 6
D   2   9   4 6 5  
E   6 1       7 9  
F   9   6     8 2  
G 9 5     3        
H 2 1     9       8
I   7     6   9   5

Step 16

Because of the number 2 just placed, the only position in column 9 for another 2 is cell G9.

1 2 3 4 5 6 7 8 9
A 1 4 9   2 6   8 7
B 6   7   4   2   9
C     2   7 9   4 6
D   2   9   4 6 5  
E   6 1       7 9  
F   9   6     8 2  
G 9 5     3       2
H 2 1     9       8
I   7     6   9   5

Step 17

The number 5 is missing from box A1-C3 and its only possible position is cell C1.

1 2 3 4 5 6 7 8 9
A 1 4 9   2 6   8 7
B 6   7   4   2   9
C 5   2   7 9   4 6
D   2   9   4 6 5  
E   6 1       7 9  
F   9   6     8 2  
G 9 5     3       2
H 2 1     9       8
I   7     6   9   5

Step 18

Because of the number 5 just placed, the only position in column 3 for another 5 is cell F3.

1 2 3 4 5 6 7 8 9
A 1 4 9   2 6   8 7
B 6   7   4   2   9
C 5   2   7 9   4 6
D   2   9   4 6 5  
E   6 1       7 9  
F   9 5 6     8 2  
G 9 5     3       2
H 2 1     9       8
I   7     6   9   5

Step 19

The number 5 does not yet appear in column 7. Due to other 5s on the grid, the only place it can go is cell A7.

1 2 3 4 5 6 7 8 9
A 1 4 9   2 6 5 8 7
B 6   7   4   2   9
C 5   2   7 9   4 6
D   2   9   4 6 5  
E   6 1       7 9  
F   9 5 6     8 2  
G 9 5     3       2
H 2 1     9       8
I   7     6   9   5

Step 20

A4 is the last empty cell in row A and the missing number is 3.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6   7   4   2   9
C 5   2   7 9   4 6
D   2   9   4 6 5  
E   6 1       7 9  
F   9 5 6     8 2  
G 9 5     3       2
H 2 1     9       8
I   7     6   9   5

Step 21

The number 5 is missing from column 5 and its only possible position is cell E5.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6   7   4   2   9
C 5   2   7 9   4 6
D   2   9   4 6 5  
E   6 1   5   7 9  
F   9 5 6     8 2  
G 9 5     3       2
H 2 1     9       8
I   7     6   9   5

Step 22

The number 8 is missing from column 5 and its only possible position is cell D5.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6   7   4   2   9
C 5   2   7 9   4 6
D   2   9 8 4 6 5  
E   6 1   5   7 9  
F   9 5 6     8 2  
G 9 5     3       2
H 2 1     9       8
I   7     6   9   5

Step 23

Because of the number 8 just placed, the only position in row E for another 8 is cell E1.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6   7   4   2   9
C 5   2   7 9   4 6
D   2   9 8 4 6 5  
E 8 6 1   5   7 9  
F   9 5 6     8 2  
G 9 5     3       2
H 2 1     9       8
I   7     6   9   5

Step 24

F5 is the last empty cell in column 5 and the missing number is 1.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6   7   4   2   9
C 5   2   7 9   4 6
D   2   9 8 4 6 5  
E 8 6 1   5   7 9  
F   9 5 6 1   8 2  
G 9 5     3       2
H 2 1     9       8
I   7     6   9   5

Step 25

Because of the number 1 just placed, the only position in row D for another 1 is cell D9.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6   7   4   2   9
C 5   2   7 9   4 6
D   2   9 8 4 6 5 1
E 8 6 1   5   7 9  
F   9 5 6 1   8 2  
G 9 5     3       2
H 2 1     9       8
I   7     6   9   5

Step 26

The number 7 is missing from row D and its only possible position is cell D1.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6   7   4   2   9
C 5   2   7 9   4 6
D 7 2   9 8 4 6 5 1
E 8 6 1   5   7 9  
F   9 5 6 1   8 2  
G 9 5     3       2
H 2 1     9       8
I   7     6   9   5

Step 27

Because of the number 7 just placed, the only position in row F for another 7 is cell F6.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6   7   4   2   9
C 5   2   7 9   4 6
D 7 2   9 8 4 6 5 1
E 8 6 1   5   7 9  
F   9 5 6 1 7 8 2  
G 9 5     3       2
H 2 1     9       8
I   7     6   9   5

Step 28

D3 is the last empty cell in row D and the missing number is 3.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6   7   4   2   9
C 5   2   7 9   4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1   5   7 9  
F   9 5 6 1 7 8 2  
G 9 5     3       2
H 2 1     9       8
I   7     6   9   5

Step 29

F1 is the last empty cell in box D1-F3 and the missing number is 4.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6   7   4   2   9
C 5   2   7 9   4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1   5   7 9  
F 4 9 5 6 1 7 8 2  
G 9 5     3       2
H 2 1     9       8
I   7     6   9   5

Step 30

Because of the number 4 just placed, the only position in row E for another 4 is cell E9.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6   7   4   2   9
C 5   2   7 9   4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1   5   7 9 4
F 4 9 5 6 1 7 8 2  
G 9 5     3       2
H 2 1     9       8
I   7     6   9   5

Step 31

F9 is the last empty cell in box D7-F9 and the missing number is 3.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6   7   4   2   9
C 5   2   7 9   4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1   5   7 9 4
F 4 9 5 6 1 7 8 2 3
G 9 5     3       2
H 2 1     9       8
I   7     6   9   5

Step 32

Because of the number 3 just placed, the only position in row E for another 3 is cell E6.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6   7   4   2   9
C 5   2   7 9   4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1   5 3 7 9 4
F 4 9 5 6 1 7 8 2 3
G 9 5     3       2
H 2 1     9       8
I   7     6   9   5

Step 33

E4 is the last empty cell in box D4-F6 and the missing number is 2.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6   7   4   2   9
C 5   2   7 9   4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1 2 5 3 7 9 4
F 4 9 5 6 1 7 8 2 3
G 9 5     3       2
H 2 1     9       8
I   7     6   9   5

Step 34

Because of the number 2 just placed, the only position in column 6 for another 2 is cell I6.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6   7   4   2   9
C 5   2   7 9   4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1 2 5 3 7 9 4
F 4 9 5 6 1 7 8 2 3
G 9 5     3       2
H 2 1     9       8
I   7     6 2 9   5

Step 35

I1 is the last empty cell in column 1 and the missing number is 3.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6   7   4   2   9
C 5   2   7 9   4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1 2 5 3 7 9 4
F 4 9 5 6 1 7 8 2 3
G 9 5     3       2
H 2 1     9       8
I 3 7     6 2 9   5

Step 36

Cell H6 can only contain the number 5 since all other numbers are somewhere in its row, column or box.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6   7   4   2   9
C 5   2   7 9   4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1 2 5 3 7 9 4
F 4 9 5 6 1 7 8 2 3
G 9 5     3       2
H 2 1     9 5     8
I 3 7     6 2 9   5

Step 37

Because of the number 5 just placed, the only position in column 4 for another 5 is cell B4.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6   7 5 4   2   9
C 5   2   7 9   4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1 2 5 3 7 9 4
F 4 9 5 6 1 7 8 2 3
G 9 5     3       2
H 2 1     9 5     8
I 3 7     6 2 9   5

Step 38

Cell I8 can only contain the number 1 since all other numbers are somewhere in its row, column or box.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6   7 5 4   2   9
C 5   2   7 9   4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1 2 5 3 7 9 4
F 4 9 5 6 1 7 8 2 3
G 9 5     3       2
H 2 1     9 5     8
I 3 7     6 2 9 1 5

Step 39

Because of the number 1 just placed, the only position in column 7 for another 1 is cell C7.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6   7 5 4   2   9
C 5   2   7 9 1 4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1 2 5 3 7 9 4
F 4 9 5 6 1 7 8 2 3
G 9 5     3       2
H 2 1     9 5     8
I 3 7     6 2 9 1 5

Step 40

Because of the number 1 just placed, the only position in row B for another 1 is cell B6.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6   7 5 4 1 2   9
C 5   2   7 9 1 4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1 2 5 3 7 9 4
F 4 9 5 6 1 7 8 2 3
G 9 5     3       2
H 2 1     9 5     8
I 3 7     6 2 9 1 5

Step 41

Because of the number 1 just placed, the only position in column 4 for another 1 is cell G4.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6   7 5 4 1 2   9
C 5   2   7 9 1 4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1 2 5 3 7 9 4
F 4 9 5 6 1 7 8 2 3
G 9 5   1 3       2
H 2 1     9 5     8
I 3 7     6 2 9 1 5

Step 42

C4 is the last empty cell in box A4-C6 and the missing number is 8.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6   7 5 4 1 2   9
C 5   2 8 7 9 1 4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1 2 5 3 7 9 4
F 4 9 5 6 1 7 8 2 3
G 9 5   1 3       2
H 2 1     9 5     8
I 3 7     6 2 9 1 5

Step 43

Because of the number 8 just placed, the only position in row B for another 8 is cell B2.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6 8 7 5 4 1 2   9
C 5   2 8 7 9 1 4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1 2 5 3 7 9 4
F 4 9 5 6 1 7 8 2 3
G 9 5   1 3       2
H 2 1     9 5     8
I 3 7     6 2 9 1 5

Step 44

G6 is the last empty cell in column 6 and the missing number is 8.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6 8 7 5 4 1 2   9
C 5   2 8 7 9 1 4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1 2 5 3 7 9 4
F 4 9 5 6 1 7 8 2 3
G 9 5   1 3 8     2
H 2 1     9 5     8
I 3 7     6 2 9 1 5

Step 45

Because of the number 8 just placed, the only position in column 3 for another 8 is cell I3.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6 8 7 5 4 1 2   9
C 5   2 8 7 9 1 4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1 2 5 3 7 9 4
F 4 9 5 6 1 7 8 2 3
G 9 5   1 3 8     2
H 2 1     9 5     8
I 3 7 8   6 2 9 1 5

Step 46

C2 is the last empty cell in box A1-C3 and the missing number is 3.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6 8 7 5 4 1 2   9
C 5 3 2 8 7 9 1 4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1 2 5 3 7 9 4
F 4 9 5 6 1 7 8 2 3
G 9 5   1 3 8     2
H 2 1     9 5     8
I 3 7 8   6 2 9 1 5

Step 47

B8 is the last empty cell in row B and the missing number is 3.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6 8 7 5 4 1 2 3 9
C 5 3 2 8 7 9 1 4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1 2 5 3 7 9 4
F 4 9 5 6 1 7 8 2 3
G 9 5   1 3 8     2
H 2 1     9 5     8
I 3 7 8   6 2 9 1 5

Step 48

Because of the number 3 just placed, the only position in column 7 for another 3 is cell H7.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6 8 7 5 4 1 2 3 9
C 5 3 2 8 7 9 1 4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1 2 5 3 7 9 4
F 4 9 5 6 1 7 8 2 3
G 9 5   1 3 8     2
H 2 1     9 5 3   8
I 3 7 8   6 2 9 1 5

Step 49

I4 is the last empty cell in row I and the missing number is 4.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6 8 7 5 4 1 2 3 9
C 5 3 2 8 7 9 1 4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1 2 5 3 7 9 4
F 4 9 5 6 1 7 8 2 3
G 9 5   1 3 8     2
H 2 1     9 5 3   8
I 3 7 8 4 6 2 9 1 5

Step 50

H4 is the last empty cell in box G4-I6 and the missing number is 7.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6 8 7 5 4 1 2 3 9
C 5 3 2 8 7 9 1 4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1 2 5 3 7 9 4
F 4 9 5 6 1 7 8 2 3
G 9 5   1 3 8     2
H 2 1   7 9 5 3   8
I 3 7 8 4 6 2 9 1 5

Step 51

Because of the number 7 just placed, the only position in row G for another 7 is cell G8.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6 8 7 5 4 1 2 3 9
C 5 3 2 8 7 9 1 4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1 2 5 3 7 9 4
F 4 9 5 6 1 7 8 2 3
G 9 5   1 3 8   7 2
H 2 1   7 9 5 3   8
I 3 7 8 4 6 2 9 1 5

Step 52

G7 is the last empty cell in column 7 and the missing number is 4.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6 8 7 5 4 1 2 3 9
C 5 3 2 8 7 9 1 4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1 2 5 3 7 9 4
F 4 9 5 6 1 7 8 2 3
G 9 5   1 3 8 4 7 2
H 2 1   7 9 5 3   8
I 3 7 8 4 6 2 9 1 5

Step 53

Because of the number 4 just placed, the only position in row H for another 4 is cell H3.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6 8 7 5 4 1 2 3 9
C 5 3 2 8 7 9 1 4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1 2 5 3 7 9 4
F 4 9 5 6 1 7 8 2 3
G 9 5   1 3 8 4 7 2
H 2 1 4 7 9 5 3   8
I 3 7 8 4 6 2 9 1 5

Step 54

G3 is the last empty cell in box G1-I3 and the missing number is 6.

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6 8 7 5 4 1 2 3 9
C 5 3 2 8 7 9 1 4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1 2 5 3 7 9 4
F 4 9 5 6 1 7 8 2 3
G 9 5 6 1 3 8 4 7 2
H 2 1 4 7 9 5 3   8
I 3 7 8 4 6 2 9 1 5

Step 55

H8 is the last empty cell in row H and the missing number is 6.

Congratulations - the puzzle is solved!

1 2 3 4 5 6 7 8 9
A 1 4 9 3 2 6 5 8 7
B 6 8 7 5 4 1 2 3 9
C 5 3 2 8 7 9 1 4 6
D 7 2 3 9 8 4 6 5 1
E 8 6 1 2 5 3 7 9 4
F 4 9 5 6 1 7 8 2 3
G 9 5 6 1 3 8 4 7 2
H 2 1 4 7 9 5 3 6 8
I 3 7 8 4 6 2 9 1 5
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