Compound Interest

Program to calculate Compound Interest :-

#include<iostream.h>
#include<conio.h>
#include<math.h>
#include<conio.h>

void main()
 {
  double p,R,y,t,n,r,a,z1,z2,z3;
  cout<<"\t\tWELCOME TO CI CALC";
  getch();
  cout<<"Enter Principal Amount:";
  cin>>p;
  cout<<"Enter rate P.A.:";
  cin>>R;
  cout<<"Enter no. of years";
  cin>>y;
   cout<<"Enter no. of times compounded per year :";
  cin>>t;
  n=t*y;
  r=R/t;
  z1=100+r;
  z2=z1/100;
  z3=pow(z2,n);
  a=p*z3;
  cout<<"\nThe total amount is :"<<a;
   cout<<"\nThe Interest is :"<<(a-p);
   cout<<"\nThe new principal is :"<<a;
  getch();
 }