Coulumb's Fource and Gravitational Force(do_while loop)

/*******************************************************
  Name: Coulumb's Fource and Gravitational Force
  Copyright: BCS-1A
  Author: Mohammad Hussnain Imtiaz
  Date: 12/01/12 00:08
  Description: USE OF DO WHILE AND SWITCH
********************************************************/
 // PREPROCESSER DIRECTICE
 #include<iostream>
 #include<conio.h>
 #include<cmath>

 using namespace std ;

 int main ()
 {
     // LOCAL DECLARATION
 double q1=0.0,
        q2=0.0,
        cRadius=0.0,
        F=0.0,
        k=pow(9.0*10,9),
        m1=0.0,
        m2=0.0,
        Fg=0.0,
        G=pow(6.674*10,-11),
        gRadius=0.0;
 int choice=0;
 char choice2 ;
        cout << "Program to calculate Coulumb's Fource & Gravitational Force\n" ;
     do
     {
        cout<< "\n\nPress 1 to calculate Coulumb's Force\n2 to calculate Gravitational Force ? " ;
        cin >> choice;
       
        switch (choice)
        {
        case 1:
        cout << "Enter the value of q1 :" ;
        cin  >> q1;
        cout << "Enter the value of q2 :" ;
        cin  >> q2;
        cout << "Enter   the    Radius :" ;
        cin  >> cRadius;
       
        F = (k * ( (q1*q2)/(pow(cRadius,2 ))));
        cout << "The Coulumb's Force is :" << F ;
        break ;
       
        case 2:
        cout << "Enter the value of m1 :" ;
        cin  >> m1;
        cout << "Enter the value of m2 :" ;
        cin  >> m2;
        cout << "Enter   the    Radius :" ;
        cin  >> gRadius;
       
        Fg = (G * ( (m1*m2)/(pow(gRadius,2 ))));
        cout << "The Gravitational Force is :" << Fg ;
        break ;
       
        default :
        cout << "You enter invalid Selection." ;
        } // end of switch statmant
        cout << "\n\n\nFor the continution of program (y/n)? ";
        cin  >> choice2 ;
        system("CLS");
        }while (choice2 == 'Y' || choice2 == 'y');
          system ("CLS");
 cout << "\n\n\n\n\n\n\n\n\n  "
      << "                    "
      << "Created By:Mohammad Hussnain Imtiaz" ;
 getch();
 return 0;  
 } // end of main function