2        7      4
        4          9
          2    6 3 7
   8    6 5 (3)  1   2
   3             8  
 5   2    1 8    7  
 9 5 4    7         
 8          4       
 3      2          8

Row/Column Elimination

In row 4, the only valid location for a three is in column 6. Columns 2, 4, 5, 7 and 9 are filled with values other than three. Columns 1 and 3 of row 4 are in the same 3×3 box with the three in cell (5,2). Column 8 of row 4 is in the same column with the three in cell (3,8).

 
 2          7      4
        4          9
          2    6 3 7
   8    6 5 3  1   2
   3             8  
 5   2    1 8    7  
 9 5 4    7         
 8 (2)        4       
 3      2          8

Box Elimination

In the 3×3 box in the lower left corner (box 7), the only valid location for a two is in cell (8,2); that is, in row 8, column 2. Five cells in that box are filled with values other than two, and the other three locations are in the same row as cell (9,4) or in the same column as cell (6,3). Since each 3×3 box must have a two, the cell (8,2) must be two.

 
 2          7      4
        4          9
          2    6 3 7
   8    6 5 3  1   2
   3             8  
 5   2  (9) 1 8    7  
 9 5 4    7         
 8 2        4       
 3      2          8

Cell Elimination

The only possible value for cell (6,4) is nine. The other eight values are located somewhere in the same row, column or box.

 

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Thanks,
Steve