SUDOKU

Write a number from 1 to 9 into each empty square in the grid so that every number from 1 to 9 appears exactly once in each horizontal row, each vertical column, and each 3×3 block.
  23      74  
48          12
1      5      3
          6      
    4  9  6    
      4  1      
8      3        
56          37
  49        2  
* Easy