Step 0

Starting puzzle

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

Step 1

The number 1 does not yet appear in row B. Due to other 1s on the grid, the only place it can go is cell B7.

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

Step 2

The number 4 does not yet appear in row A. Due to other 4s on the grid, the only place it can go is cell A8.

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

Step 3

The number 1 does not yet appear in row F. Due to other 1s on the grid, the only place it can go is cell F2.

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

Step 4

The number 6 does not yet appear in row D. Due to other 6s on the grid, the only place it can go is cell D8.

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

Step 5

The number 6 does not yet appear in row H. Due to other 6s on the grid, the only place it can go is cell H4.

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

Step 6

Because of the number 6 just placed, the only position in column 5 for another 6 is cell C5.

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

Step 7

Because of the number 6 just placed, the only position in row B for another 6 is cell B2.

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

Step 8

C4 is the last empty cell in column 4 and the missing number is 3.

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

Step 9

The number 7 does not yet appear in row G. Due to other 7s on the grid, the only place it can go is cell G8.

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

Step 10

Because of the number 7 just placed, the only position in column 9 for another 7 is cell C9.

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

Step 11

Because of the number 7 just placed, the only position in row A for another 7 is cell A1.

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

Step 12

Because of the number 7 just placed, the only position in column 2 for another 7 is cell E2.

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

Step 13

The number 1 does not yet appear in column 5. Due to other 1s on the grid, the only place it can go is cell G5.

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

Step 14

Because of the number 1 just placed, the only position in row H for another 1 is cell H3.

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

Step 15

The number 2 does not yet appear in column 6. Due to other 2s on the grid, the only place it can go is cell G6.

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

Step 16

Because of the number 2 just placed, the only position in row I for another 2 is cell I2.

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

Step 17

I5 is the last empty cell in box G4-I6 and the missing number is 5.

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

Step 18

B6 is the last empty cell in column 6 and the missing number is 5.

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

Step 19

Because of the number 5 just placed, the only position in row C for another 5 is cell C2.

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

Step 20

A5 is the last empty cell in box A4-C6 and the missing number is 9.

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

Step 21

A3 is the last empty cell in row A and the missing number is 2.

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

Step 22

Because of the number 2 just placed, the only position in row C for another 2 is cell C8.

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

Step 23

Because of the number 2 just placed, the only position in column 9 for another 2 is cell E9.

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

Step 24

Because of the number 2 just placed, the only position in column 1 for another 2 is cell D1.

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

Step 25

B1 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 7 3 2 8 9 1 6 4 5
B 9 6 4 7 2 5 1    
C 1 5 8 3 6 4   2 7
D 2     5   9 7 6 1
E   7   1 8 6     2
F 4 1 6 2   7      
G       4 1 2 8 7 6
H     1 6 7 3 2    
I 6 2 7 9 5 8   1  

Step 26

C7 is the last empty cell in row C and the missing number is 9.

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

Step 27

The number 4 does not yet appear in column 2. Due to other 4s on the grid, the only place it can go is cell H2.

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

Step 28

The number 8 does not yet appear in row H. Due to other 8s on the grid, the only place it can go is cell H1.

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

Step 29

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

Step 30

G2 is the last empty cell in column 2 and the missing number is 9.

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

Step 31

Because of the number 9 just placed, the only position in column 3 for another 9 is cell E3.

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

Step 32

The number 4 does not yet appear in column 5. Due to other 4s on the grid, the only place it can go is cell D5.

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

Step 33

Because of the number 4 just placed, the only position in row E for another 4 is cell E7.

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

Step 34

Because of the number 4 just placed, the only position in column 9 for another 4 is cell I9.

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

Step 35

F5 is the last empty cell in box D4-F6 and the missing number is 3.

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

Step 36

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

Step 37

Because of the number 3 just placed, the only position in row E for another 3 is cell E8.

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

Step 38

Because of the number 3 just placed, the only position in column 1 for another 3 is cell G1.

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

Step 39

I7 is the last empty cell in row I and the missing number is 3.

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

Step 40

Because of the number 3 just placed, the only position in column 9 for another 3 is cell B9.

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

Step 41

B8 is the last empty cell in box A7-C9 and the missing number is 8.

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

Step 42

Because of the number 8 just placed, the only position in column 9 for another 8 is cell F9.

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

Step 43

E1 is the last empty cell in box D1-F3 and the missing number is 5.

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

Step 44

G3 is the last empty cell in column 3 and the missing number is 5.

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

Step 45

Because of the number 5 just placed, the only position in row H for another 5 is cell H8.

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

Step 46

Because of the number 5 just placed, the only position in row F for another 5 is cell F7.

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

Step 47

F8 is the last empty cell in box D7-F9 and the missing number is 9.

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

Step 48

H9 is the last empty cell in column 9 and the missing number is 9.

Congratulations - the puzzle is solved!

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