01  #include <math.h>
02  #include <stdio.h>
03  
04  int main()
05  {
06    double num = 123.54;
07    double down_value;
08  
09    down_value = floor(num);
10  
11    printf("original number     %5.2lfn", num);
12    printf("number rounded down   %5.2lfn", down_value);
13  
14    return 0;
15  } 

 
 OUTPUT :
 
 original number     123.54
 number rounded down   123.00