SUDOKU #16        
             
I'm going to repeat the info at the top of Sudoku #1, just in case you haven't seen that one yet.  
             
I've been doing Sudoku for a while. There are a lot of people like me who have figured out some tricks or techniques that help them complete the puzzles. This page is not really for them. I met a woman recently who was just starting to try to do Sudoku. This page is for people like her. I'm not saying that I know every single trick, but I know enough to complete most puzzles.  
             
The basic rules of Sudoku are that there is only one of each number in each row, column, and 16 square grid. You won't need to do mathematics or arithmetic. If you know how to count from 1 to 16, then you can do these puzzles. All of the techniques are based on these rules. Each puzzle starts with some boxes filled in. As you solve the puzzle, the grid becomes a 'house of cards'. Make one mistake, and many of the boxes filled in later may be wrong. So Sudoku is like a house of cards.  
             
I've been working on 16x16 puzzles for quite a while. Here is a sample Sudoku puzzle. It might be good to just print out this grid and write in the numbers as I go. There may be times when I do more numbers in one step than can be followed just by looking at the webpage.  
             
  A     7   3   8   12   13 16     1        
  B 6 1 16 3     9   14     8 11 15 5        
  C       8 6             11              
  D 5 10     11   14       9       12        
  E 3 5 12         6     8     9 16        
  F 10       12     2 5     4   7          
  G 8 6   1     3 15   7 14       2        
  H   7   15   13       16 1   8 12          
  I     10 5   3 16       4   1   15        
  J   2       12 15   1 14     10   6 7      
  K     1   2     8 7     5       13      
  L   13 6     1     8         11 14 5      
  M   4       10       8   14     7 16      
  N         14             2 12            
  O   12 9 10 15     1   3     2 14 8 11      
  P   11     8 16   3   9   10   13          
    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16      
         
This is an evil version of a Sudoku puzzle. I've added the letters below to the rows and columns in order to talk about each of the 256 squares. As a convention, I will talk about squares and boxes. There are 256 squares, but there are 16 boxes of 16 squares.  
                 
  A     7   3   8   12   13 16     1        
  B 6 1 16 3     9 12 14     8 11 15 5        
  C 12     8 6   1         11              
  D 5 10     11   14       9 1     12        
  E 3 5 12   1     6     8     9 16        
  F 10       12     2 5     4   7   1      
  G 8 6   1     3 15   7 14 12     2        
  H   7   15   13       16 1   8 12          
  I     10 5   3 16       4   1   15 12      
  J   2       12 15   1 14     10   6 7      
  K     1   2     8 7     5       13      
  L   13 6     1     8         11 14 5      
  M   4       10       8   14   1 7 16      
  N         14         1   2 12            
  O   12 9 10 15     1   3     2 14 8 11      
  P 1 11     8 16   3   9   10   13          
    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16      
                                 
Because of E3,O2,A9, and D15, there is a 12 in C1. There is a 12 in B8 (note F5,J6,C1,A9, and D15). There is a 12 in I16 (note N13,H14, and D15). There is a 12 in G12 (note E3,F5,H14, and A9). There is a 1 in C7 (note L6,O8, and B2). There is a 1 in N10 (note J9,H11, and O8), a 1 in D12 (J9,N10,H11, and A16), a 1 in E5 (note L6,C7,O8,G4, and H11), a 1 in F16 (E5,G4,H11, I13, and A15), a 1 in M14 (note I13,A15,F16, and N10), and a 1 in P1 (note B2,K3,G4,M14,N10, and O8).  
                 
  A     7   3   8   12   13 16     1        
  B 6 1 16 3     9 12 14   7 8 11 15 5        
  C 12     8 6   1       7 11              
  D 5 10     11   14       9 1     12        
  E 3 5 12   1 7 7 6     8     9 16        
  F 10       12 8   2 5     4   7   1      
  G 8 6   1 16   3 15   7 14 12     2        
  H   7   15   13       16 1   8 12          
  I     10 5   3 16       4   1 2 15 12      
  J   2       12 15   1 14     10 8 6 7      
  K     1 12 2     8 7 12   5       13      
  L   13 6 12   1     8 12       11 14 5      
  M   4       10 12     8 12 14   1 7 16      
  N         14         1   2 12            
  O   12 9 10 15     1   3   7 2 14 8 11      
  P 1 11     8 16 12 3   9 12 10   13          
    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16      
                     
There is a 12 in K4 or L4 (note C1,O2,J6, and I16). There is a 12 in M7 or P7 (note F5,J6,B8,N13, and O2). There is a 12 in M11 or P11 (note A9,G12,N13, and O2). There isa 12 in K10 or L10 (note A9,G12,N13, and O2). There is a 2 in I14 (note O13,J2,K5), and a 8 in J14 (note K8,L9). There is a 16 in G5 (note B3,I7, and P6). There is a 7 in B11 or C11 (note A3,K9, and G10), so there is a 7 in O12. There is a 7 in E6 or E7 (note H2,G10, and F14). There is an 8 in F6 (note P5,A7,K8, and G1).  
               
  A     7   3   8   12   13 16     1        
  B 6 1 16 3     9 12 14   7 8 11 15 5        
  C 12     8 6   1       7 11              
  D 5 10     11   14       9 1     12 8      
  E 3 5 12   1 7 7 6     8     9 16        
  F 10 9,16   9,16 12 8   2 5     4   7   1      
  G 8 6   1 16   3 15   7 14 12     2        
  H   7   15   13       16 1   8 12          
  I   8 10 5   3 16       4   1 2 15 12      
  J   2       12 15   1 14     10 8 6 7      
  K     1 12 2     8 7 12   5       13      
  L   13 6 12   1     8 12       11 14 5      
  M   4       10 12     8 12 14   1 7 16      
  N     8   14         1   2 12            
  O   12 9 10 15     1   3   7 2 14 8 11      
  P 1 11     8 16 12 3   9 12 10   13          
    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16      
                   
There's an 8 in I2 (note K8,L9,J13, and G1), another 8 in N3 (note G1,I2,C4,M10, and P5), and another in D16 (note H13,J14,O15,A7,B12, and C4). There is a 16 in F2 or F4 (note B3,E15,G5, and H10). The 9 in Box E9H12 is in Row G or Row H (note E14,P10, and D11), and the 9 in Box E5H8 is in Row G or Row H (note E14,B7). So the 9 in Box E1H4 is either in F2 or F4.  
   
            3
4
9
10
11
13
       
  A     7   3   8   12   13 16     1        
  B 6 1 16 3     9 12 14   7 8 11 15 5   2,4,7,10,13    
  C 12     8 6   1       7 11              
  D 5 10     11   14       9 1     12 8      
  E 3 5 12   1 7 7 6     8     9 16        
  F 10 9,16 13,14 9,16 12 8 11 2 5     4   7 3,13 1 3,6,11,13,14,15  
  G 8 6   1 16   3 15   7 14 12     2   4,5,9,10,11,13  
  H   7   15   13       16 1   8 12 11        
  I   8 10 5   3 16       4   1 2 15 12 6,7,9,11,13,14  
  J   2 3     12 15   1 14     10 8 6 7      
  K   3 1 12 2     8 7 12   5     3,9 13      
  L   13 6 12   1     8 12       11 14 5      
  M   4 3     10 12     8 12 14   1 7 16      
  N   3 8   14         1   2 12            
  O   12 9 10 15     1   3   7 2 14 8 11 4,5,6,13,16    
  P 1 11     8 16 12 3   9 12 10   13 4        
    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16      
                       
There is a 3 in J3 or K2 (note E1 and B4) in M3 or N2 (note E1,B4, and P8). The numbers missing from Row B are 2,4,7,10,13. The numbers missing from Row G are 4,5,9,10,11,13. The numbers missing from Row I are 6,7,9,11,13,14. The numbers missing from Row O are 4,5,6,13,16. The numbers missing from Row F are 3,6,11,13,14,15. Box E5H8 contains the 3,6,13, and 15, and there is a 14 in D7, so F7 is 11. The numbers missing from Col 15 are 3,4,9,10,11, and 13. Box M13P16 contains 11 and 13, and Row P contains 3,9, and 10, so P15 is a 4. H15 is 11 (note B13,L14,O16, and F7). There is a 13 or 14 in F3 (since the numbers missing from Row G are 3,6,13,14, and 15, and the 3,6, and 15 are in Box E1H4).  
                   
    3
9
14
15
16
  4
5
7
9
10
13
  4
5
6
7
10
13
    3
4
5
6
10
16
3
9
10
13
       
  A     7   3   8 10 12   13 16     1        
  B 6 1 16 3 13   9 12 14   7 8 11 15 5   2,4,7,10,13    
  C 12     8 6   1 10     7 11 7   13        
  D 5 10     11   14       9 1 7   12 8      
  E 3 5 12   1 7 7 6     8     9 16        
  F 10 9,16 13 9,16 12 8 11 2 5     4   7 3 1 3,6,13,14,15  
  G 8 6   1 16   3 15   7 14 12     2   4,5,9,10,11,13  
  H   7   15   13       16 1   8 12 11        
  I 7 8 10 5 7,9 3 16       4   1 2 15 12 6,7,9,11,13,14  
  J   2 3     12 15   1 14     10 8 6 7      
  K   3 1 12 2     8 7 12   5     9 13      
  L 7 13 6 12   1     8 12       11 14 5      
  M   4 3   5,9 10 2,12     8 12 14   1 7 16      
  N   3 8   14         1   2 12   10        
  O   12 9 10 15     1   3   7 2 14 8 11 4,5,6,13,16    
  P 1 11 14 7 8 16 2,12 3   9 12 10   13 4        
    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16      
                               
The 2 in Box A5D8 is in Col 6 (note K5 and F8), so the 2 in Box M5P8 is in M7 or P7 (note N12 and O13). There is a 13 in B5 (note K16,A11, and H6). There is a 7 in P4 (note M15,O12, and A3), so there is a 14 in P3. So there is a 13 in F3, a 3 in F15, and a 9 in K15. The missing numbers from Col 15 are 10 and 13, so the 10 is in N15 (note P14) and the 13 is in C15.  
                               
    3
9
14
15
16
  4
5
7
9
10
13
  4
5
6
7
10
13
    3
4
5
6
10
16
         
  A     7   3   8 10 12   13 16     1 14      
  B 6 1 16 3 13   9 12 14   7 8 11 15 5   2,4,7,10    
  C 12     8 6   1 10     7 11 7   13 14      
  D 5 10     11   14       9 1 7   12 8      
  E 3 5 12   1 7 7 6     8     9 16        
  F 10 9,16 13 9,16 12 8 11 2 5 6,15 6,15 4 14 7 3 1 6,14,15  
  G 8 6   1 16   3 15   7 14 12     2   4,5,9,10,11,13  
  H   7   15   13     3 16 1 3 8 12 11        
  I 7 8 10 5 7,9 3 16 13     4   1 2 15 12 6,7,9,11,13,14  
  J   2 3     12 15 13 1 14     10 8 6 7      
  K   3 1 12 2     8 7 12   5     9 13      
  L 7 13 6 12   1     8 12       11 14 5      
  M   4 3   5,9 10 12     8 12 14   1 7 16      
  N   3 8   14   13     1   2 12   10        
  O   12 9 10 15   13 1   3   7 2 14 8 11 4,5,6,13,16    
  P 1 11 14 7 8 16 2 3 6,15 9 12 10 5 13 4 6,15 2,5,6,12,15    
    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16      
                       
There is a 14 in F13 (note G11). There is a 13 in I8 or J8 (note B5,H6,K16, and L2), and a 13 in N7 or O7. The missing numbers from Row P are 2,5,6,12, and 15. P9 has to be the 6 or 15 (note the 5 and 12 in Col 9 and the 2 in N12), and P16 has to be the 6 or 15 (note the 2 and 12 in Box M13P16 and the 5 in L16). So the missing numbers in Row P are now the 2,5, and 12, and the 5 would be in P13 (note N13 and O13). So the missing numbers in Row P are the 2 and 12, but there is a 2 in N12, so the 2 is in P11 and the 12 is in P7 - which means that the 12 is in M7.  
                       
    3
9
14
15
16
  4
5
7
9
10
  4
5
6
7
10
13
    3
4
5
6
10
16
         
  A     7   3   8 10 12 5 13 16     1 14      
  B 6 1 16 3 13   9 12 14   7 8 11 15 5   2,4,7,10    
  C 12     8 6   1 10   5 7 11 7   13 14      
  D 5 10   13 11   14       9 1 7   12 8      
  E 3 5 12   1 7 7 6     8   15 9 16        
  F 10 9,16 13 9,16 12 8 11 2 5 6,15 6,15 4 14 7 3 1    
  G 8 6   1 16   3 15   7 14 12 13   2   4,5,9,10,11,13  
  H   7   15   13     3 16 1 3 8 12 11 6      
  I 7 8 10 5 7,9 3 16 13     4   1 2 15 12 6,7,9,11,13,14  
  J   2 3     12 15 13 1 14     10 8 6 7      
  K   3 1 12 2 6 6 8 7 12   5     9 13      
  L 7 13 6 12   1     8 12       11 14 5      
  M   4 3   5,9 10 12     8   14   1 7 16      
  N   3 8   14   13     1   2 12 3,6 10        
  O 13,16 12 9 10 15 6 6,13 1   3   7 2 14 8 11 4,5,6,13,16    
  P 1 11 14 7 8 16 2 3 6 9 12 10 5 13 4 15      
    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16      
  2,4,9,11,14,15
-
-
2,3,5,6,13,15,16
2,4,5,7,10,15,16
4,5,7,9,10,14
-
2,3,9,10,11,13
-
4,5,
6,11,13,15,16
-
4,5,
6,10,13,15
3,4,16
3,6,9,
15
     
                   
There is a 13 in D4 (note A11,B5,C15, and F3). There is a 6 in H16 (note E8,G2, and F10/F11), so there is a 15 in P16, and a 6 in P9. There is a 15 in E13 (note B14,I15,P16, and G8). There isa 13 in G13 (note P14,C15,K16).  
                           
    3
9
14
15
16
2
3
4
5
11
15
  4
5
7
9
10
  4
5
6
7
10
13
    3
6
9
13
15
3
4
6
7
9
16
3
4
5
6
10
16
  2
3
4
9
10
14
     
  A     7   3   8 10 12 5 13 16     1 14      
  B 6 1 16 3 13   9 12 14   7 8 11 15 5 2 2,4,7,10    
  C 12     8 6   1 10   5 7 11 7   13 14      
  D 5 10   13 11   14       9 1 7   12 8      
  E 3 5 12   1 7 7 6   13 8 13 15 9 16 4,10      
  F 10 9,16 13 9,16 12 8 11 2 5 6,15 6,15 4 14 7 3 1    
  G 8 6   1 16   3 15   7 14 12 13 5 2 4,10 4,5,9,10,11  
  H   7   15   13     3 16 1 3 8 12 11 6      
  I 7 8 10 5 7,9 3 16 13     4   1 2 15 12 6,7,9,11,13,14  
  J   2 3     12 15 13 1 14     10 8 6 7      
  K   3 1 12 2 6 6 8 7 12   5     9 13      
  L 7 13 6 12   1     8 12       11 14 5      
  M   4 3 6 5,9 10 12     8   14   1 7 16      
  N   3 8 6 14   13     1   2 12 3,6 10 3,9      
  O 13,16 12 9 10 15 6 6,13 1   3   7 2 14 8 11 4,5,6,13,16    
  P 1 11 14 7 8 16 2 3 6 9 12 10 5 13 4 15      
    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16      
  2,4,9,11,14,15
-
-
2,3,5,6,13,15,16
2,4,5,7,10,15,16
4,5,7,9,10,14
-
2,3,9,10,11,13
-
4,5,11,13,15,16
-
-
3,4,16
3,6,9
     
                       
There is a 5 in G14 (note L16). Then there is a 4 and 10 in E16 and G16, so the missing numbers in Col 16 are 2,3,9,14. So there is a 2 in B16 (note B4,B7, and B9 or E16,G16, and J16).  
                       
    3
9
14
15
16
2
3
4
5
11
15
  4
5
7
9
10
  4
5
6
7
10
13
    3
6
9
13
15
3
4
6
7
9
16
3
4
6
10
16
  3
9
14
     
  A     7   3   8 10 12 5 13 16     1 14      
  B 6 1 16 3 13   9 12 14   7 8 11 15 5 2 4,7,10    
  C 12     8 6   1 10   5 7 11 7   13 14      
  D 5 10   13 11   14       9 1 7   12 8 2,3,4,6,7,15,16  
  E 3 5 12   1 7 7 6   13 8 13 15 9 16 4,10      
  F 10 9,16 13 9,16 12 8 11 2 5 15 6 4 14 7 3 1    
  G 8 6 4,11 1 16 4,9 3 15   7 14 12 13 5 2 4,10 4,9,10,11  
  H   7 2,4 15   13     3 16 1 3,9 8 12 11 6 2,3,4,5,9,10,14  
  I 7 8 10 5 7,9 3 16 13   6 4 6 1 2 15 12 6,7,9,11,13,14  
  J   2 3     12 15 13 1 14     10 8 6 7      
  K   15 1 12 2 6 6 8 7 12   5     9 13      
  L 7 13 6 12 7 1     8 12       11 14 5      
  M   4 5 6 5,9 10 12     8   14 3 1 7 16      
  N   3 8 6 14   13     1   2 12 6 10 9      
  O 13,16 12 9 10 15 6 6,13 1   3   7 2 14 8 11 4,5,6,13,16    
  P 1 11 14 7 8 16 2 3 6 9 12 10 5 13 4 15      
    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16      
  2,4,9,11,14,15
2,4,11,14
-
2,
3,5,6,13,15,16
2,4,5,7,10,15,16
4,5,7,9,10,14
-
2,3,9,10,11,13
-
4,5,11,13,15,16
-
-
3,4,16
3,6,9
     
                   
The 6 in Row I is in I10 or I12, and the 6 in Box A9D12 is in Col 10 or Col 12 (note P9,B1, and C5). So, since Col 10 and 12 are covered for the 6s, the 6 in Box E9H12 is in F11, and the 15 is in F10. The 3 and 5 in Box M1P4 are in M3 and N2. The 3 and 15 are in J3 and K2 (note H4), so the 15 is in K2 (note J7) and the 3 is in J3, and the 3 is in N2, and the 5 is in M3 (note also E2). There is a 3 in M13 (note N2), a 6 in N14, and a 9 in N16.  
                   
    9
14
16
2
4
11
15
  4
5
7
9
10
  4
5
6
7
10
13
    3
6
9
13
15
4
6
7
9
16
3
4
10
16
  3
14
     
  A   9 7   3   8 10 12 5 13 16   10 1 14      
  B 6 1 16 3 13 4,7 9 12 14 10 7,10 8 11 15 5 2 4,7,10    
  C 12 14   8 6   1 10   5 7 11 7 10 13 3      
  D 5 10   13 11   14   3   9 1 7   12 8 2,3,4,6,7,15,16  
  E 3 5 12   1 7 7 6   13 8 13 15 9 16 4,10      
  F 10 16 13 9 12 8 11 2 5 15 6 4 14 7 3 1    
  G 8 6 4,11 1 16 4,9 3 15   7 14 12 13 5 2 4,10 4,9,10,11  
  H   7 2,4 15   13       16 1 3 8 12 11 6 2,3,4,5,9,10,14  
  I 7 8 10 5 7,9 3 16 13   6 4 6 1 2 15 12 6,7,9,11,13,14  
  J   2 3     12 15 13 1 14     10 8 6 7      
  K   15 1 12 2 6 6 8 7 12   5 4,16 3 9 13      
  L 7 13 6 12 7 1     8 12     4,16 11 14 5      
  M   4 5 6 5,9 10 12 9   8   14 3 1 7 16      
  N   3 8   14   13     1   2 12 6 10 9      
  O 13,16 12 9 10 15 6 6,13 1   3   7 2 14 8 11 4,5,6,13,16    
  P 1 11 14 7 8 16 2 3 6 9 12 10 5 13 4 15      
    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16      
  2,4,9,11,14,15
2,4,11,14
-
2,
6,13,15,16
2,4,5,7,10,15,16
4,5,7,9,10,14
-
2,
3,9,10,11,13
-
4,5,11,13,15,16
-
-
3,4,16
3,6,9
     
                   
The missing numbers from Col 16 are 3 and 14. There is a 14 in A16 (note A5), and a 3 in C16. There is a 3 in D9 (note C16,B4,A5,O10), and another 3 in H12. The 10 in Col 8 are in either Row A or C, and the 10 in Col 14 is in either Row A or C, so the 10 in Box A9D12 is either in B10 or B11 (note D2). The missing numbers from Col 2 are 9,14, and 16, but there is a 14 in A16 and another in F13, so there is a 14 in C2. The other way to look at C2 is to see that the 14 in A16 leaves a 9 and 16 in A2, and A2 matches F2, cancelling each other out, after which only the 14 is missing from Col 2, so it is in C2. There is a 9 in A2 (note B3), a 16 in F2, and a 9 in F4.  
                     
      2
4
11
15
  4
5
7
9
10
  4
5
6
7
10
13
    6
9
13
15
6
7
9
4
10
16
         
  A   9 7   3   8 10 12 5 13 16   10 1 14      
  B 6 1 16 3 13 4,7 9 12 14 4,10 7,10 8 11 15 5 2 4,7,10    
  C 12 14   8 6   1 10   5 7 11 7 10 13 3      
  D 5 10   13 11   14   3   9 1 7   12 8 2,3,4,6,7,15,16  
  E 3 5 12   1 7 7 6     8 13 15 9 16 4,10      
  F 10 16 13 9 12 8 11 2 5 15 6 4 14 7 3 1    
  G 8 6 4,11 1 16 4,9 3 15 9 7 14 12 13 5 2 4,10 4,9,10,11  
  H   7 2,4 15   13     9 16 1 3 8 12 11 6 2,4,5,9,10,14  
  I 7 8 10 5 7,9 3 16   11 13 4 6 1 2 15 12 6,7,9,11,13,14  
  J   2 3     12 15 13 1 14   9 10 8 6 7      
  K   15 1 12 2 6 6 8 7 12   5 4,16 3 9 13      
  L 7 13 6 12 7 1     8 12   9 4,16 11 14 5      
  M   4 5 6 5,9 10 12 9   8   14 3 1 7 16      
  N   3 8   14   13     1   2 12 6 10 9      
  O 13,16 12 9 10 15 6 6,13 1   3   7 2 14 8 11 4,5,6,13,16    
  P 1 11 14 7 8 16 2 3 6 9 12 10 5 13 4 15      
    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16      
  2,4,9,11,14,15
2,4,11,14
-
2,13,15,16
2,4,5,7,10,15,16
4,5,7,9,10,14
-
2,9,10,11,
13
-
4,5,11,13,15,16
-
-
-
-
     
                                         
The missing numbers from Col 12 are 6,9,13,15, and 16, so there is a 13 in E12, and there is a 13 in I10 (note A11,E12,K16, and L2), which means that a 6 is in I12. The missing numbers from Row I are 7,9,11,14, so the 11 is in I9 (note K9,B9, and G9-H9). There is a 13 in J8 (note I10,L2,B5,H6).  
                                         
      2
4
11
15
  4
5
7
9
10
  4
5
6
7
10
13
    9
15
6
7
9
4
10
16
         
  A   9 7   3   8 10 12 5 13 16   10 1 14      
  B 6 1 16 3 13 4 9 12 14 10 7 8 11 15 5 2 4,7,10    
  C 12 14   8 6   1 10   5   11 7 10 13 3      
  D 5 10   13 11   14   3   9 1 7   12 8 2,3,4,6,7,15,16  
  E 3 5 12   1 7 7 6     8 13 15 9 16 4,10      
  F 10 16 13 9 12 8 11 2 5 15 6 4 14 7 3 1    
  G 8 6 4,11 1 16 4,9 3 15 9 7 14 12 13 5 2 4,10 4,9,10,11  
  H   7 2,4 15   13     9 16 1 3 8 12 11 6 2,4,5,9,10,14  
  I 7 8 10 5 7,9 3 16   11 13 4 6 1 2 15 12 7,9,14  
  J   2 3     12 15 13 1 14 16 9 10 8 6 7      
  K   15 1 12 2 6 6 8 7 12 10 5 4,16 3 9 13      
  L 7 13 6 12 7 1     8 2 3 15 4,16 11 14 5      
  M   4 5 6 5,9 10 12 9   8   14 3 1 7 16      
  N   3 8   14   13   16 1   2 12 6 10 9      
  O 13,16 12 9 10 15 6 6,13 1 16 3   7 2 14 8 11 4,5,6,13,16    
  P 1 11 14 7 8 16 2 3 6 9 12 10 5 13 4 15      
    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16      
  2,4,9,11,15
2,4,11,14
-
2,13,15,16
2,4,5,7,10,15,16
4,5,7,9,10,14
-
2,9,10,11
2,3,10,12,16
4,5,11,13,15,16
-
-
-
-
     
                                         
The missing numbers in Col 12 are 9 and 15, so the 15 is in L12 (note J7), and the 9 is in J12. There is a 3 in L11 (note J3,K14, and O10). There is a 2 in L10 (note J2 and K5), a 12 in K10, a 10 in K11 (note J13). There is a 7 in B11, a 10 in B10, and a 4 in B6.  
                                         
      2
4
11
15
  4
5
7
9
10
  4
5
6
7
10
13
      6
7
9
4
10
16
         
  A   9 7   3   8 10 12 5 13 16   10 1 14      
  B 6 1 16 3 13 4 9 12 14 10 7 8 11 15 5 2      
  C 12 14   8 6   1 10   5   11 7 10 13 3      
  D 5 10   13 11   14   3   9 1 7   12 8 2,3,4,6,7,15,16  
  E 3 5 12   1 7 7 6 2 11 8 13 15 9 16 10      
  F 10 16 13 9 12 8 11 2 5 15 6 4 14 7 3 1    
  G 8 6 11 1 16 9 3 15 10 7 14 12 13 5 2 4 4,9,10,11  
  H   7 2,4 15   13     9 16 1 3 8 12 11 6 2,4,5,9,10,14  
  I 7 8 10 5 7,9 3 16   11 13 4 6 1 2 15 12 7,9,14  
  J   2 3     12 15 13 1 14 16 9 10 8 6 7 4,5,11  
  K   15 1   2 6 6 8 7 12 10 5 4,16 3 9 13      
  L 7 13 6 12 7 1     8 2 3 15 4,16 11 14 5      
  M   4 5 6 5,9 10 12 9   8 11 14 3 1 7 16      
  N   3 8   14   13   16 1 5,11 2 12 6 10 9      
  O 13,16 12 9 10 15 6 6,13 1 16 3 5 7 2 14 8 11 4,5,6,13,16    
  P 1 11 14 7 8 16 2 3 6 9 12 10 5 13 4 15      
    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16      
  2,4,9,11,15
2,4,11,14
-
2,13,15,16
2,4,5,7,10,15,16
4,5,7,9,10,14
-
2,9,10,11
-
4,5,11,13,15,16
-
-
-
-
     
                                         
There is a 9 in G6 (note B6), a 9 in H11. There's a 12 in L4 (note K10). The numbers missing from Row G are 4,10, and 11. There is an 11 in G3 (note I9 and O16), a 10 in G9 (note F12), a 4 in G16, and a 10 in E16.  
                                         
      2
4
15
2
4
11
14
16
4
5
7
9
10
  4
5
6
7
10
13
  4
5
6
    6
7
9
4
10
16
         
  A   9 7   3 15 8 10 12 5 13 16   10 1 14      
  B 6 1 16 3 13 4 9 12 14 10 7 8 11 15 5 2      
  C 12 14 15 8 6   1 10 2,15 5 2,15 11 7 10 13 3      
  D 5 10 15 13 11   14   3   9 1 7   12 8 2,4,6,7,15,16  
  E 3 5 12 4,14 1 7,14 4,7 6 2 11 8 13 15 9 16 10 4,7,14  
  F 10 16 13 9 12 8 11 2 5 15 6 4 14 7 3 1    
  G 8 6 11 1 16 9 3 15 10 7 14 12 13 5 2 4    
  H   7 2,4 15   13     9 16 1 3 8 12 11 6 2,4,5,10,14  
  I 9 8 10 5 7 3 16   11 13 4 6 1 2 15 12 7,9,14  
  J   2 3     12 15 13 1 14 16 9 10 8 6 7 4,5,11  
  K   15 1   2 6 6 8 7 12 10 5 4,16 3 9 13      
  L 7 13 6 12   1   9 8 2 3 15 4,16 11 14 5      
  M   4 5 6 9 10 12     8 11 14 3 1 7 16      
  N   3 8   14   13   16 1 5,11 2 12 6 10 9      
  O 13,16 12 9 10 15 6 6,13 1 16 3 5 7 2 14 8 11 4,5,6,13,16    
  P 1 11 14 7 8 16 2 3 6 9 12 10 5 13 4 15      
    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16      
  2,4,11,15
2,4,14
-
2,13,15,16
2,5,7,10,15,16
4,5,7,10,14
-
-
-
-
-
-
-
-
     
                                         
One of the missing numbers in Row A is a 15. The 15 cannot be in A1 or A4 (note H4) or the A10 (note F10) or in Box O13D16 (note B14), or A8 (note G8), so it has to be in A6. There is a 9 in M5 (note M2,M3,M15,M6), a 7 in I5 (note M5, N5), and a 7 in L1. There is a 9 in I1 (note J12, K15), and another 9 is in L8 (note I1,J12,K15,M5, and B7). The missing numbers from Col 10 are 4,5,6, so the numbers missing from Box A9D12 are 2 and 15.  
                                         
        2
4
15
2
4
11
14
16
4
5
7
9
10
  4
5
6
7
10
13
  4
5
6
    6
7
9
4
10
16
         
  A 2,11 9 7 2,11 3 15 8 10 12   13 16   10 1 14      
  B 6 1 16 3 13 4 9 12 14 10 7 8 11 15 5 2      
  C 12 14 4 8 6   1 10 15 5 2 11 7 10 13 3      
  D 5 10 15 13 11   14   3   9 1 7   12 8 2,4,6,7,15,16  
  E 3 5 12 4,14 1 7,14 4,7 6 2 11 8 13 15 9 16 10 4,7,14  
  F 10 16 13 9 12 8 11 2 5 15 6 4 14 7 3 1    
  G 8 6 11 1 16 9 3 15 10 7 14 12 13 5 2 4    
  H 4,14 7 2 15   13     9 16 1 3 8 12 11 6 2,4,5,10,14  
  I 9 8 10 5 7 3 16   11 13 4 6 1 2 15 12 7,9,14  
  J   2 3     12 15 13 1 14 16 9 10 8 6 7 4,5,11  
  K   15 1   2 6 6 8 7 12 10 5 4,16 3 9 13      
  L 7 13 6 12   1   9 8 2 3 15 4,16 11 14 5      
  M   4 5 6 9 10 12   13 8 11,15 14 3 1 7 16      
  N   3 8   14   13   4,16 1 11,15 2 12 6 10 9      
  O 13,16 12 9 10 15 6 6,13 1 4,16 3 5 7 2 14 8 11 4,5,6,13,16    
  P 1 11 14 7 8 16 2 3 6 9 12 10 5 13 4 15      
    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16      
    2,4,11,15
2,4,14
-
2,13,15,16
2,5,7,10,16
4,5,7,10,14
-
-
-
4,13,16
-
-
-
-
     
                                         
There is a 15 in D3 (note C9 and M9, along with B14 and A6). There is a 4 in C3 (note C9 and M9), so there is a 2 in H3. The numbers missing from Col 11 are 2,5,11, and 15. So there is a 5 in O11 (note O13,O16, and O5), and there is a 2 in C11 (note N12), and a 15 in C9. The missing number in Box A9D12 are the 4,5, and 6, so the 5 is in C10. The missing numbers in Col 11 are the 11 and 15, so the missing numbers in Box M9P12 are 4,13, and 16. There is a 13 in M9 (note M2 and M16).  
                                         
          2
4
11
14
16
4
5
10
  4
5
6
7
10
13
  4
6
    6
7
9
4
10
16
         
  A 2,11 9 7 2,11 3 15 8 10 12   13 16   10 1 14      
  B 6 1 16 3 13 4 9 12 14 10 7 8 11 15 5 2      
  C 12 14 4 8 6   1 10 15 5 2 11 7 10 13 3      
  D 5 10 15 13 11   14   3   9 1 7   12 8 2,4,6,7,16  
  E 3 5 12 4 1 14 7 6 2 11 8 13 15 9 16 10 4,7,14  
  F 10 16 13 9 12 8 11 2 5 15 6 4 14 7 3 1    
  G 8 6 11 1 16 9 3 15 10 7 14 12 13 5 2 4    
  H 14 7 2 15   13     9 16 1 3 8 12 11 6 4,5,10,14  
  I 9 8 10 5 7 3 16 14 11 13 4 6 1 2 15 12 14  
  J   2 3     12 15 13 1 14 16 9 10 8 6 7 4,5,11  
  K   15 1   2   6 8 7 12 10 5 4,16 3 9 13      
  L 7 13 6 12   1   9 8 2 3 15 4,16 11 14 5      
  M   4 5 6 9 10 12   13 8 11,15 14 3 1 7 16      
  N   3 8   14   13   4,16 1 11,15 2 12 6 10 9      
  O 13,16 12 9 10 15 6 13 1 4,16 3 5 7 2 14 8 11 4,6,13,16    
  P 1 11 14 7 8 16 2 3 6 9 12 10 5 13 4 15      
    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16      
    2,4,11,15
2,4,14
-
2,13,15,16
2,5,7,10,16
4,5,7,10,14
-
-
-
4,16
-
-
-
-
     
                                         
The only missing number from Row I is a 14, so the 14 is in I8, so there is another 14 in E6 (note N5,D7, and I8) - which means there is a 4 in E4 and a 7 in E7 and a 14 in H1. The numbers missing from Row O are 4,6,13,16, so there is a 6 in O6 (note B6,H6, and P6) and a 6 in K7.  
                                         
          2
11
14
16
4
5
10
  4
5
10
13
  4
6
    6
7
9
4
10
16
         
  A 11 9 7 2 3 15 8 5 12 4 13 16 6 10 1 14 4,5,6,10  
  B 6 1 16 3 13 4 9 12 14 10 7 8 11 15 5 2      
  C 12 14 4 8 6 7 1 10 15 5 2 11 9 16 13 3 7,9,10,14,16  
  D 5 10 15 13 11 2 14 16 3 6 9 1 7 4 12 8 2,4,6,7,16  
  E 3 5 12 4 1 14 7 6 2 11 8 13 15 9 16 10    
  F 10 16 13 9 12 8 11 2 5 15 6 4 14 7 3 1    
  G 8 6 11 1 16 9 3 15 10 7 14 12 13 5 2 4    
  H 14 7 2 15   13     9 16 1 3 8 12 11 6 4,5,10  
  I 9 8 10 5 7 3 16 14 11 13 4 6 1 2 15 12    
  J   2 3     12 15 13 1 14 16 9 10 8 6 7 4,5,11  
  K   15 1   2   6 8 7 12 10 5 4,16 3 9 13      
  L 7 13 6 12   1   9 8 2 3 15 4,16 11 14 5      
  M 2 4 5 6 9 10 12   13 8 11,15 14 3 1 7 16 2,11,15  
  N   3 8   14   13   4,16 1 11,15 2 12 6 10 9      
  O 13,16 12 9 10 15 6 13 1 4,16 3 5 7 2 14 8 11 4,13,16    
  P 1 11 14 7 8 16 2 3 6 9 12 10 5 13 4 15      
    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16      
    2,4,11,15
2,4,14
-
2,13,15,16
2,5,7,10,16
4,5,7,10,14
4,6
-
-
-
-
-
-
-
     
                                         
The numbers missing from Col 13 are the 6,7,9, so there is a 9 in C13 (note A2,D11), a 7 in D13, and a 6 in A13. There is a 6 in D10 and a 4 in A10. There is a 10 in A14, a 5 in A8, and a 10 in C8. There is a 7 in C6 and a 16 in C14, a 4 in D14, a 16 in D8 (note F8), and a 2 in D6. There is a 2 in M1 (note P7,N12, and O13), so there is a 11 in A1 and a 2 in A4.  
                                         
          2
11
14
16
4
5
10
  4
5
10
13
  4
6
                 
  A 11 9 7 2 3 15 8 5 12 4 13 16 6 10 1 14    
  B 6 1 16 3 13 4 9 12 14 10 7 8 11 15 5 2      
  C 12 14 4 8 6 7 1 10 15 5 2 11 9 16 13 3    
  D 5 10 15 13 11 2 14 16 3 6 9 1 7 4 12 8    
  E 3 5 12 4 1 14 7 6 2 11 8 13 15 9 16 10    
  F 10 16 13 9 12 8 11 2 5 15 6 4 14 7 3 1    
  G 8 6 11 1 16 9 3 15 10 7 14 12 13 5 2 4    
  H 14 7 2 15   13   4 9 16 1 3 8 12 11 6 4,5,10  
  I 9 8 10 5 7 3 16 14 11 13 4 6 1 2 15 12    
  J   2 3     12 15 13 1 14 16 9 10 8 6 7 4,5,11  
  K   15 1   2 11 6 8 7 12 10 5 4,16 3 9 13      
  L 7 13 6 12   1   9 8 2 3 15 4,16 11 14 5      
  M 2 4 5 6 9 10 12 11 13 8 15 14 3 1 7 16 2,11,15  
  N 15 3 8 16 14 5 13 7 4 1 11 2 12 6 10 9      
  O 13 12 9 10 15 6 4 1 16 3 5 7 2 14 8 11 4,13,16    
  P 1 11 14 7 8 16 2 3 6 9 12 10 5 13 4 15      
    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16      
                                         
There is a 15 in N1 (note O5 and H4), a 16 in N4 (note D4), and a 16 in O1. There is a 11 in N11 and a 15 in M11. There is a 4 in N9 and a 16 in O9. There is a 13 in N7. The only missing number in Row O is a 4, so the 4 is in O7. The missing numbers in Row H are 4,5, and 10, so the 4 is in H8 (note A8 and C8). The only missing number from Row M is a 11, so the 11 is in M8, and the only number missing from Col 8 is a 7, so the 7 is in N8. The only number missing from Row N is a 5, so the 5 is in N6. The only number missing from Col 6 is 11, so there is an 11 in K6.  
                                         
  A 11 9 7 2 3 15 8 5 12 4 13 16 6 10 1 14    
  B 6 1 16 3 13 4 9 12 14 10 7 8 11 15 5 2      
  C 12 14 4 8 6 7 1 10 15 5 2 11 9 16 13 3    
  D 5 10 15 13 11 2 14 16 3 6 9 1 7 4 12 8    
  E 3 5 12 4 1 14 7 6 2 11 8 13 15 9 16 10    
  F 10 16 13 9 12 8 11 2 5 15 6 4 14 7 3 1    
  G 8 6 11 1 16 9 3 15 10 7 14 12 13 5 2 4    
  H 14 7 2 15 10 13 5 4 9 16 1 3 8 12 11 6    
  I 9 8 10 5 7 3 16 14 11 13 4 6 1 2 15 12    
  J 4 2 3 11 5 12 15 13 1 14 16 9 10 8 6 7    
  K 16 15 1 14 2 11 6 8 7 12 10 5 4 3 9 13      
  L 7 13 6 12 4 1 10 9 8 2 3 15 16 11 14 5      
  M 2 4 5 6 9 10 12 11 13 8 15 14 3 1 7 16    
  N 15 3 8 16 14 5 13 7 4 1 11 2 12 6 10 9      
  O 13 12 9 10 15 6 4 1 16 3 5 7 2 14 8 11      
  P 1 11 14 7 8 16 2 3 6 9 12 10 5 13 4 15      
    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16      
                                         
The numbers missing in Col 7 are 5 and 10, so the 10 is in L7 (note L16), and the 5 is in H7. Then the 10 is in H5. The missing numbers in Row L are 4 and 16, so the 4 is in L5 (note G5), the 16 is in L13, the 4 is in K13. The number missing from Box I5L8 is a 5, so the 5 is in J5. The numbers missing from Box I1L4 are 4,11,14,16, so the 16 is in K1 (note N4 and J11), the 4 is in J1, the 11 is in J4, and the 14 is in K4.  
                                         
  A 11 9 7 2 3 15 8 5 12 4 13 16 6 10 1 14      
  B 6 1 16 3 13 4 9 12 14 10 7 8 11 15 5 2      
  C 12 14 4 8 6 7 1 10 15 5 2 11 9 16 13 3      
  D 5 10 15 13 11 2 14 16 3 6 9 1 7 4 12 8      
  E 3 5 12 4 1 14 7 6 2 11 8 13 15 9 16 10      
  F 10 16 13 9 12 8 11 2 5 15 6 4 14 7 3 1      
  G 8 6 11 1 16 9 3 15 10 7 14 12 13 5 2 4      
  H 14 7 2 15 10 13 5 4 9 16 1 3 8 12 11 6      
  I 9 8 10 5 7 3 16 14 11 13 4 6 1 2 15 12      
  J 4 2 3 11 5 12 15 13 1 14 16 9 10 8 6 7      
  K 16 15 1 14 2 11 6 8 7 12 10 5 4 3 9 13      
  L 7 13 6 12 4 1 10 9 8 2 3 15 16 11 14 5      
  M 2 4 5 6 9 10 12 11 13 8 15 14 3 1 7 16      
  N 15 3 8 16 14 5 13 7 4 1 11 2 12 6 10 9      
  O 13 12 9 10 15 6 4 1 16 3 5 7 2 14 8 11      
  P 1 11 14 7 8 16 2 3 6 9 12 10 5 13 4 15      
    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16      
                                         
                                         
 
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