Code:#include<iostream.h> void main() { float sum,difference,product,qoutient,a,b; char mychoice,password,answer; cout<<"enter your password"<<endl; cin>>password; if(password=='v') { cout<<"access granted....."<<endl; cout<<"do you want to perform one of the four mathematical operations?"<<endl; cout<<"mychoice"<<endl; cout<<"a for addition"<<endl; cout<<"s for subtraction"<<endl; cout<<"m for multiplication"<<endl; cout<<"d for division"<<endl; cout<<"enter your choice"<<endl; cin>>answer; while(answer=='Y')//(answer!='N') { cout<<"mychoice"<<endl; cout<<"a for addition"<<endl; cout<<"s for subtraction"<<endl; cout<<"m for multiplication"<<endl; cout<<"d for division"<<endl; cout<<"enter your choice"<<endl; cin>>mychoice; switch (mychoice) { case'a': cout<<"enter first number"<<endl; cin>>a; cout<<"enter second number"<<endl; cin>>b; sum=a+b; cout<<"the sum is:"<<sum<<endl; cout<<"do you want to continue?"<<endl; cin>>answer; break; case's': cout<<"enter first number"<<endl; cin>>a; cout<<"enter second number"<<endl; cin>>b; difference=a-b; cout<<"the difference is:"<<difference<<endl; cout<<"do you want to continue?"<<endl; cin>>answer; break; case'm': cout<<"enter first number"<<endl; cin>>a; cout<<"enter second number"<<endl; cin>>b; product=a*b; cout<<"the product is:"<<product<<endl; cout<<"do you want to continue?"<<endl; cin>>answer; break; case'd': cout<<"enter first number"<<endl; cin>>a; cout<<"enter second number"<<endl; cin>>b; qoutient=a/b; cout<<"the qoutient is:"<<qoutient<<endl; cout<<"do you want to continue?"<<endl; cin>>answer; break; default: cout<<"invalid choice"<<endl; break; } } } else cout<<"invalid password!!"<<endl; }