Step 0

Starting puzzle

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

Step 1

The number 1 does not yet appear in row A. Due to other 1s on the grid, the only place it can go is cell A2.

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

Step 2

The number 2 does not yet appear in row A. Due to other 2s on the grid, the only place it can go is cell A1.

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

Step 3

The number 1 does not yet appear in row E. Due to other 1s on the grid, the only place it can go is cell E6.

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

Step 4

The number 3 does not yet appear in row E. Due to other 3s on the grid, the only place it can go is cell E9.

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

Step 5

Because of the number 3 just placed, the only position in column 7 for another 3 is cell C7.

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

Step 6

Because of the number 3 just placed, the only position in row B for another 3 is cell B3.

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

Step 7

The number 7 does not yet appear in row E. Due to other 7s on the grid, the only place it can go is cell E8.

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

Step 8

The number 8 does not yet appear in row D. Due to other 8s on the grid, the only place it can go is cell D2.

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

Step 9

The number 1 does not yet appear in row I. Due to other 1s on the grid, the only place it can go is cell I8.

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

Step 10

The number 2 does not yet appear in column 4. Due to other 2s on the grid, the only place it can go is cell E4.

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

Step 11

Because of the number 2 just placed, the only position in row D for another 2 is cell D8.

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

Step 12

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

Step 13

Because of the number 2 just placed, the only position in row H for another 2 is cell H2.

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

Step 14

F8 is the last empty cell in box D7-F9 and the missing number is 6.

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

Step 15

D6 is the last empty cell in row D and the missing number is 5.

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

Step 16

Because of the number 5 just placed, the only position in row F for another 5 is cell F2.

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

Step 17

Because of the number 5 just placed, the only position in column 4 for another 5 is cell C4.

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

Step 18

Because of the number 5 just placed, the only position in row A for another 5 is cell A8.

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

Step 19

Because of the number 5 just placed, the only position in column 9 for another 5 is cell I9.

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

Step 20

Because of the number 5 just placed, the only position in column 3 for another 5 is cell G3.

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

Step 21

F4 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 2 1   3 4     5 7
B 5 7 3 8 1   2    
C       5   2 3   1
D 1 8 7 6 3 5 4 2 9
E     9 2 8 1 5 7 3
F 3 5 2 4 9 7 1 6 8
G 7   5 1         2
H   2 1   5 8   3 4
I 8       2 4   1 5

Step 22

B9 is the last empty cell in column 9 and the missing number is 6.

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

Step 23

The number 7 does not yet appear in row C. Due to other 7s on the grid, the only place it can go is cell C5.

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

Step 24

G5 is the last empty cell in column 5 and the missing number is 6.

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

Step 25

Because of the number 6 just placed, the only position in column 6 for another 6 is cell A6.

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

Step 26

B6 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 2 1   3 4 6   5 7
B 5 7 3 8 1 9 2   6
C       5 7 2 3   1
D 1 8 7 6 3 5 4 2 9
E     9 2 8 1 5 7 3
F 3 5 2 4 9 7 1 6 8
G 7   5 1 6       2
H   2 1   5 8   3 4
I 8       2 4   1 5

Step 27

B8 is the last empty cell in row B and the missing number is 4.

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

Step 28

G6 is the last empty cell in column 6 and the missing number is 3.

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

Step 29

Because of the number 3 just placed, the only position in row I for another 3 is cell I2.

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

Step 30

The number 4 does not yet appear in row G. Due to other 4s on the grid, the only place it can go is cell G2.

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

Step 31

The number 4 does not yet appear in row E. Due to other 4s on the grid, the only place it can go is cell E1.

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

Step 32

Because of the number 4 just placed, the only position in column 3 for another 4 is cell C3.

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

Step 33

E2 is the last empty cell in box D1-F3 and the missing number is 6.

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

Step 34

C2 is the last empty cell in column 2 and the missing number is 9.

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

Step 35

Because of the number 9 just placed, the only position in row A for another 9 is cell A7.

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

Step 36

Because of the number 9 just placed, the only position in column 1 for another 9 is cell H1.

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

Step 37

Because of the number 9 just placed, the only position in column 8 for another 9 is cell G8.

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

Step 38

Because of the number 9 just placed, the only position in row I for another 9 is cell I4.

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

Step 39

C8 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 2 1   3 4 6 9 5 7
B 5 7 3 8 1 9 2 4 6
C   9 4 5 7 2 3 8 1
D 1 8 7 6 3 5 4 2 9
E 4 6 9 2 8 1 5 7 3
F 3 5 2 4 9 7 1 6 8
G 7 4 5 1 6 3   9 2
H 9 2 1   5 8   3 4
I 8 3   9 2 4   1 5

Step 40

A3 is the last empty cell in row A and the missing number is 8.

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

Step 41

Because of the number 8 just placed, the only position in column 7 for another 8 is cell G7.

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

Step 42

C1 is the last empty cell in box A1-C3 and the missing number is 6.

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

Step 43

I3 is the last empty cell in column 3 and the missing number is 6.

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

Step 44

Because of the number 6 just placed, the only position in row H for another 6 is cell H7.

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

Step 45

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

Step 46

I7 is the last empty cell in row I and the missing number is 7.

Congratulations - the puzzle is solved!

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