C Program For Creating Simple Calculator

# include <iostream.h>
# include <conio.h>
# include <iomanip.h>
void main()
{
float a,b,c,d;
gotoxy(12,4);
cout<<"WELCOME TO SIMPLE WALKYTALKY CALCULATOR !\a\n";
cout<<" MAIN MENU\n";
cout<<"1."<<" "<<"ADDITION\n";
cout<<"2."<<" "<<"SUBTRACTION\n";
cout<<"3."<<" "<<"MULTIPLICATION\n";
cout<<"4."<<" "<<"DIVISION\n";
cout<<"5."<<" "<<"SQUARE OF NUMBER\n";
cout<<"6."<<" "<<"FACTORIAL OF NUMBER\n";
cout<<"PRESS ANY KEY OF ABOVE NUMBERS\n";
cin>>c;
cout<<"\a";
clrscr();
cout<<"\a";
if (c==1)
{cout<<"ADDITION AREA\n";
cout<<"INPUT THE NUMBERS \n";
cout<<"ENTER NO.1\n";
cin>>a;
cout<<"\a";
cout<<"ENTER NO.2\n";
cin>>b;
cout<<"\a";
cout<<"ANSWER\n";
cout<<a<<"+"<<b<<"="<<a+b;}
else if (c==2)
{cout<<"SUBTRACTION AREA\n";
cout<<"INPUT THE NUMBERS\n";
cout<<"ENTER NO.1\n";
cin>>a;
cout<<"\a";
cout<<"ENTER NO.2\n";
cin>>b;
cout<<"\a";
cout<<"ANSWER\n";
cout<<a<<"-"<<b<<"="<<a-b;}
else if (c==3)
{cout<<"MULTIPLICATION AREA\n";
cout<<"INPUT THE NUMBERS\n";
cout<<"ENTER NO.1\n";
cin>>a;
cout<<"\a";
cout<<"ENTER NO.2\n";
cin>>b;
cout<<"\a";
cout<<"ANSWER\n";
cout<<a<<"*"<<b<<"="<<a*b;}
 else if (c==4)
{cout<<"DIVISION  AREA\n";
cout<<"INPUT THE NUMBERS\n";
cout<<"ENTER NO.1\n";
cin>>a;
cout<<"\a";
cout<<"ENTER NO.2\n";
cin>>b;
cout<<"\a";
cout<<"ANSWER\n";
cout<<a<<"/"<<b<<"="<<a/b;}
else if (c==5)
{cout<<"SQUARE  AREA\n";
cout<<"INPUT A NUMBER\n";
cin>>a;
cout<<"\a";
cout<<"SQUARE OF"<<" "<<a<<" "<<"IS"<<" "<<a*a;}
else if(c==6)
{int d=1;
cout<<"FACTORIAL AREA\n";
cout<<"INPUT A NUMBER\n";
cin>>a;
cout<<"\a";
for(b=a;b>=1;b--)
{d=d*b;}
cout<<"THE FACTORIAL OF"<<" "<<a<<" "<<"IS"<<" "<<d;}
else {cout<<"ERROR !"<<" "<<c<<" "<<"NOT DEFINED IN ABOVE NUMBER";}
getch();
}