Step 0

Starting puzzle

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

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 B3.

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

Step 2

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

Step 3

The number 9 does not yet appear in column 3. Due to other 9s on the grid, the only place it can go is cell A3.

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

Step 4

The number 3 does not yet appear in column 7. Due to other 3s on the grid, the only place it can go is cell C7.

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

Step 5

The number 7 is missing from column 3 and its only possible position is cell G3.

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

Step 6

The number 4 is missing from box A7-C9 and its only possible position is cell A8.

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

Step 7

The number 7 is missing from box A7-C9 and its only possible position is cell B7.

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

Step 8

Because of the number 7 just placed, the only position in row C for another 7 is cell C2.

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

Step 9

Because of the number 7 just placed, the only position in column 1 for another 7 is cell E1.

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

Step 10

Because of the number 7 just placed, the only position in row D for another 7 is cell D5.

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

Step 11

Because of the number 7 just placed, the only position in column 8 for another 7 is cell I8.

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

Step 12

The number 6 is missing from box D1-F3 and its only possible position is cell E2.

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

Step 13

Because of the number 6 just placed, the only position in row F for another 6 is cell F8.

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

Step 14

The number 3 is missing from box D1-F3 and its only possible position is cell F3.

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

Step 15

Because of the number 3 just placed, the only position in row E for another 3 is cell E5.

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

Step 16

D2 is the last empty cell in box D1-F3 and the missing number is 8.

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

Step 17

H3 is the last empty cell in column 3 and the missing number is 8.

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

Step 18

The number 5 does not yet appear in row E. Due to other 5s on the grid, the only place it can go is cell E4.

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

Step 19

The number 3 does not yet appear in row H. Due to other 3s on the grid, the only place it can go is cell H1.

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

Step 20

Because of the number 3 just placed, the only position in column 2 for another 3 is cell A2.

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

Step 21

I2 is the last empty cell in column 2 and the missing number is 1.

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

Step 22

G1 is the last empty cell in box G1-I3 and the missing number is 4.

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

Step 23

Because of the number 4 just placed, the only position in row H for another 4 is cell H7.

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

Step 24

The number 6 is missing from column 7 and its only possible position is cell G7.

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

Step 25

The number 2 is missing from column 7 and its only possible position is cell D7.

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

Step 26

Because of the number 2 just placed, the only position in row E for another 2 is cell E6.

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

Step 27

Because of the number 2 just placed, the only position in column 8 for another 2 is cell G8.

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

Step 28

D4 is the last empty cell in row D and the missing number is 9.

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

Step 29

Because of the number 9 just placed, the only position in row E for another 9 is cell E9.

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

Step 30

I7 is the last empty cell in column 7 and the missing number is 9.

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

Step 31

E8 is the last empty cell in box D7-F9 and the missing number is 8.

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

Step 32

Because of the number 8 just placed, the only position in column 9 for another 8 is cell I9.

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

Step 33

H9 is the last empty cell in box G7-I9 and the missing number is 5.

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

Step 34

I5 is the last empty cell in row I and the missing number is 5.

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

Step 35

The number 2 does not yet appear in row B. Due to other 2s on the grid, the only place it can go is cell B5.

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

Step 36

Because of the number 2 just placed, the only position in column 4 for another 2 is cell H4.

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

Step 37

H5 is the last empty cell in row H and the missing number is 6.

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

Step 38

Because of the number 6 just placed, the only position in column 4 for another 6 is cell C4.

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

Step 39

G4 is the last empty cell in column 4 and the missing number is 8.

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

Step 40

The number 8 does not yet appear in row B. Due to other 8s on the grid, the only place it can go is cell B6.

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

Step 41

Because of the number 8 just placed, the only position in column 5 for another 8 is cell F5.

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

Step 42

F6 is the last empty cell in box D4-F6 and the missing number is 4.

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

Step 43

Because of the number 4 just placed, the only position in column 5 for another 4 is cell C5.

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

Step 44

The number 9 does not yet appear in row C. Due to other 9s on the grid, the only place it can go is cell C6.

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

Step 45

Because of the number 9 just placed, the only position in column 5 for another 9 is cell G5.

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

Step 46

A5 is the last empty cell in box A4-C6 and the missing number is 1.

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

Step 47

G6 is the last empty cell in column 6 and the missing number is 1.

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

Step 48

A1 is the last empty cell in row A and the missing number is 6.

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

Step 49

Because of the number 6 just placed, the only position in row B for another 6 is cell B9.

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

Step 50

B1 is the last empty cell in box A1-C3 and the missing number is 1.

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

Step 51

C9 is the last empty cell in row C and the missing number is 1.

Congratulations - the puzzle is solved!

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