i have done this code which can do add, sub, mul, div and square. But this much function is not sufficient for a calculator. I want to add one exponential function and one square root function. plz help me frens

Code:

#include <iostream>
int main()
{
double num;
double num2;
char choice;
for (;;){
do {
cout<<"\n";
cout<<"Welcome to apex calculator.\n";
cout<<"Please choose an option by entering the number, press q to quit\n";
cout<<"1 - Addition\n";
cout<<"2 - Subtraction\n";
cout<<"3 - Division\n";
cout<<"4 - Multiplication\n";
cout<<"5 - Help\n";
cout<<"6 - About This Program\n";
cout<<"7 - find square\n";
cin>>choice;
} while ( choice < '1' || choice > '7' && choice != 'q');
if (choice == 'q') break;
switch (choice) {
case '1':
cout<<"Please enter a number\n";
cin>>num;
cout<<"Another number to be added\n";
cin>>num2;
cout<<num + num2;
cout<<"\n";
break;
case '2':
cout<<"Please enter a number\n";
cin>>num;
cout<<"Another number to be subtracted\n";
cin>>num2;
cout<<num - num2;
cout<<"\n";
break;
case '3':
cout<<"Please enter a number\n";
cin>>num;
cout<<"Another one to be divided\n";
cin>>num2;
cout<<num / num2;
cout<<"\n";
break;
case '4':
cout<<"Please enter a number\n";
cin>>num;
cout<<"Another one to be multiplied\n";
cin>>num2;
cout<<num * num2;
cout<<"\n";
break;
case '5':
cout<<"This is a simple calculator made by bishal, manoj, pramesh and ram\n";
cout<<"To select an option, type the number next to the option and press enter\n";
cout<<"E.G. for division, you would type 3 and press enter.\n";
cout<<"\n";
break;
case '6':
cout<<" apex calculator, made by bishal, manoj, pramesh and ram \n";
cout<<"\n";
break;
case '7':
cout<<"please enter a number\n";
cin>>num;
cout<<"the square is \t "<<num*num;
cout<<"\n";
break;
default:
cout<<"That is not an option";
}
}
return 0;
}