Step 0

Starting puzzle

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

Step 1

The number 5 does not yet appear in row B. Due to other 5s on the grid, the only place it can go is cell B5.

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

Step 2

The number 4 does not yet appear in row F. Due to other 4s on the grid, the only place it can go is cell F8.

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

Step 3

The number 3 does not yet appear in column 6. Due to other 3s on the grid, the only place it can go is cell H6.

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

Step 4

Because of the number 3 just placed, the only position in row I for another 3 is cell I8.

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

Step 5

The number 6 is missing from box A4-C6 and its only possible position is cell A5.

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

Step 6

Because of the number 6 just placed, the only position in column 4 for another 6 is cell F4.

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

Step 7

Because of the number 6 just placed, the only position in row E for another 6 is cell E7.

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

Step 8

The number 2 is missing from row E and its only possible position is cell E3.

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

Step 9

E5 is the last empty cell in row E and the missing number is 9.

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

Step 10

Because of the number 9 just placed, the only position in column 4 for another 9 is cell G4.

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

Step 11

The number 8 is missing from column 5 and its only possible position is cell H5.

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

Step 12

I5 is the last empty cell in column 5 and the missing number is 7.

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

Step 13

I4 is the last empty cell in box G4-I6 and the missing number is 2.

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

Step 14

Because of the number 2 just placed, the only position in column 6 for another 2 is cell C6.

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

Step 15

The number 1 is missing from box A4-C6 and its only possible position is cell A6.

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

Step 16

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

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

Step 17

Because of the number 1 just placed, the only position in column 4 for another 1 is cell D4.

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

Step 18

Because of the number 1 just placed, the only position in row F for another 1 is cell F2.

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

Step 19

Because of the number 1 just placed, the only position in column 9 for another 1 is cell H9.

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

Step 20

Because of the number 1 just placed, the only position in column 1 for another 1 is cell I1.

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

Step 21

B4 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 2   5 7 6 1      
B     1 8 5 9   6  
C       4 3 2 1   5
D 6     1 4       7
E 5 4 2 3 9 7 6 1 8
F 7 1   6 2     4 3
G 3     9 1 4      
H   2   5 8 3 4   1
I 1     2 7 6 8 3 9

Step 22

The number 4 does not yet appear in row I. Due to other 4s on the grid, the only place it can go is cell I3.

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

Step 23

Because of the number 4 just placed, the only position in column 1 for another 4 is cell B1.

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

Step 24

Because of the number 4 just placed, the only position in row A for another 4 is cell A9.

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

Step 25

I2 is the last empty cell in row I and the missing number is 5.

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

Step 26

The number 6 does not yet appear in column 9. Due to other 6s on the grid, the only place it can go is cell G9.

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

Step 27

Because of the number 6 just placed, the only position in row H for another 6 is cell H3.

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

Step 28

Because of the number 6 just placed, the only position in column 2 for another 6 is cell C2.

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

Step 29

B9 is the last empty cell in column 9 and the missing number is 2.

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

Step 30

The number 9 does not yet appear in row H. Due to other 9s on the grid, the only place it can go is cell H1.

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

Step 31

H8 is the last empty cell in row H and the missing number is 7.

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

Step 32

Because of the number 7 just placed, the only position in column 7 for another 7 is cell B7.

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

Step 33

Because of the number 7 just placed, the only position in row C for another 7 is cell C3.

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

Step 34

Because of the number 7 just placed, the only position in column 2 for another 7 is cell G2.

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

Step 35

G3 is the last empty cell in box G1-I3 and the missing number is 8.

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

Step 36

B2 is the last empty cell in row B and the missing number is 3.

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

Step 37

Because of the number 3 just placed, the only position in row A for another 3 is cell A7.

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

Step 38

Because of the number 3 just placed, the only position in column 3 for another 3 is cell D3.

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

Step 39

C1 is the last empty cell in column 1 and the missing number is 8.

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

Step 40

Because of the number 8 just placed, the only position in row A for another 8 is cell A8.

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

Step 41

Because of the number 8 just placed, the only position in column 2 for another 8 is cell D2.

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

Step 42

Because of the number 8 just placed, the only position in row F for another 8 is cell F6.

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

Step 43

A2 is the last empty cell in box A1-C3 and the missing number is 9.

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

Step 44

C8 is the last empty cell in row C and the missing number is 9.

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

Step 45

F3 is the last empty cell in column 3 and the missing number is 9.

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

Step 46

Because of the number 9 just placed, the only position in row D for another 9 is cell D7.

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

Step 47

D6 is the last empty cell in box D4-F6 and the missing number is 5.

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

Step 48

F7 is the last empty cell in row F and the missing number is 5.

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

Step 49

Because of the number 5 just placed, the only position in column 8 for another 5 is cell G8.

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

Step 50

D8 is the last empty cell in box D7-F9 and the missing number is 2.

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

Step 51

G7 is the last empty cell in column 7 and the missing number is 2.

Congratulations - the puzzle is solved!

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