find simple interest and take value of n as default argument in C++

 Write a program to find simple interest and take value of n as default argument

#include<iostream.h>

#include<conio.h>

float interest(float p,float r, float n=5);

float interest(float p,float r,float n)

{

float i=(p*r*n)/100;

return i;

}

void main()

{

float p,r;

cout<<"\n enter the value of P";

cin>>p;

cout<<"\n enter the value of R";

cin>>r;

cout<<"\n the simple interest is  ";

cout<<interest(p,r);

getch();

}