Step 0

Starting puzzle

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

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

Step 2

The number 1 does not yet appear in column 3. Due to other 1s on the grid, the only place it can go is cell F3.

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

Step 3

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 H7.

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

Step 4

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

Step 5

The number 4 is missing from row E and its only possible position is cell E5.

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

Step 6

E8 is the last empty cell in row E and the missing number is 3.

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

Step 7

The number 3 is missing from column 7 and its only possible position is cell B7.

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

Step 8

Because of the number 3 just placed, the only position in row C for another 3 is cell C2.

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

Step 9

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

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

Step 10

The number 7 is missing from column 2 and its only possible position is cell B2.

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

Step 11

Cell D4 can only contain the number 8 since all other numbers are somewhere in its row, column or box.

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

Step 12

Cell A5 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     5 3 1   7 8  
B   7     5   3 2  
C 1 3     9   5   4
D     9 8 6     7  
E 7 6 2 5 4 1 9 3 8
F   8 1   2   4    
G 6   3   8       7
H   9         8    
I   1       5 6    

Step 13

Because of the number 1 just placed, the only position in row B for another 1 is cell B9.

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

Step 14

The number 1 does not yet appear in row D. Due to other 1s on the grid, the only place it can go is cell D7.

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

Step 15

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

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

Step 16

Because of the number 2 just placed, the only position in column 9 for another 2 is cell D9.

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

Step 17

The number 9 is missing from box A7-C9 and its only possible position is cell A9.

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

Step 18

Because of the number 9 just placed, the only position in row B for another 9 is cell B1.

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

Step 19

C8 is the last empty cell in box A7-C9 and the missing number is 6.

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

Step 20

Because of the number 6 just placed, the only position in column 9 for another 6 is cell F9.

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

Step 21

F8 is the last empty cell in box D7-F9 and the missing number is 5.

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

Step 22

Because of the number 5 just placed, the only position in column 9 for another 5 is cell H9.

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

Step 23

Because of the number 5 just placed, the only position in row G for another 5 is cell G2.

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

Step 24

Because of the number 5 just placed, the only position in column 1 for another 5 is cell D1.

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

Step 25

I9 is the last empty cell in column 9 and the missing number is 3.

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

Step 26

The number 4 does not yet appear in row D. Due to other 4s on the grid, the only place it can go is cell D2.

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

Step 27

F1 is the last empty cell in box D1-F3 and the missing number is 3.

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

Step 28

D6 is the last empty cell in row D and the missing number is 3.

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

Step 29

Because of the number 3 just placed, the only position in column 5 for another 3 is cell H5.

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

Step 30

A2 is the last empty cell in column 2 and the missing number is 2.

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

Step 31

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

Step 32

Because of the number 7 just placed, the only position in row H for another 7 is cell H3.

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

Step 33

The number 6 does not yet appear in column 3. Due to other 6s on the grid, the only place it can go is cell B3.

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

Step 34

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

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

Step 35

Because of the number 6 just placed, the only position in column 4 for another 6 is cell H4.

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

Step 36

A1 is the last empty cell in row A and the missing number is 4.

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

Step 37

Because of the number 4 just placed, the only position in column 3 for another 4 is cell I3.

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

Step 38

C3 is the last empty cell in box A1-C3 and the missing number is 8.

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

Step 39

Because of the number 8 just placed, the only position in row B for another 8 is cell B6.

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

Step 40

Because of the number 8 just placed, the only position in column 1 for another 8 is cell I1.

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

Step 41

H1 is the last empty cell in box G1-I3 and the missing number is 2.

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

Step 42

Because of the number 2 just placed, the only position in row I for another 2 is cell I4.

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

Step 43

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

Step 44

B4 is the last empty cell in row B and the missing number is 4.

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

Step 45

C4 is the last empty cell in box A4-C6 and the missing number is 7.

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

Step 46

Because of the number 7 just placed, the only position in column 6 for another 7 is cell F6.

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

Step 47

F4 is the last empty cell in box D4-F6 and the missing number is 9.

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

Step 48

Because of the number 9 just placed, the only position in column 6 for another 9 is cell G6.

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

Step 49

I8 is the last empty cell in row I and the missing number is 9.

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

Step 50

G4 is the last empty cell in column 4 and the missing number is 1.

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

Step 51

Because of the number 1 just placed, the only position in row H for another 1 is cell H8.

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

Step 52

H6 is the last empty cell in box G4-I6 and the missing number is 4.

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

Step 53

G8 is the last empty cell in row G and the missing number is 4.

Congratulations - the puzzle is solved!

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