Write a programe for Calculation of simple interest

#include< stdio.h >
#include< conio.h >

void main( )
{
int p, n ;
float r, si ;
clrscr();
p = 1000 ;
n = 3 ;
r = 8.5 ;

/* formula for simple interest */
si = p * n * r / 100 ;

printf ( "%f" , si ) ;
getch();
}