Who knew writing a calculator program could be so tough? :P

Code:

#include <iostream>
#include <string>
using namespace std;
void plus();
void minus();
void multi();
void divi();
void calc() {
string cal;
cout << "Do you want to add, subtract, multiply, or divide?\n";
cin.ignore(80,'\n');
cin >> cal;
if (cal == "add" || "Add") {
plus();
}
else if (cal == "subtract" || "subtract") {
minus();
}
else if (cal == "multiply" || "Multiply") {
multi();
}
else if (cal == "divide" || "Divide") {
divi();
}
}
void again() {
string d;
cin >> d;
if (d == "Y" || "y") {
calc();
}
else {
}
}
int main()
{
string a;
cout << "Do you wish to use the Calculator? Y/N: ";
cin >> a;
if (a == "Y" || "y")
{
calc();
cout << "Would you like to use the calculator again? Y/N: ";
cin >> a;
while (a == "Y" || "y")
{
again();
cout << "Would you like to use the calculator again? Y/N: ";
cin >> a;
}
}
else
{
cin.ignore(80,'\n');
}
return 0;
}
void plus() {
float a;
float b;
float c;
cout << "Input a number: ";
cin >> a;
cout << "Input a second number: ";
cin >> b;
c = a + b;
cout << a << " plus " << b << " equals " << c << ".";
cin.ignore(80,'\n');
cin.get();
}
void minus() {
float a;
float b;
float c;
cout << "Input the number you want to subtract from: ";
cin >> a;
cout << "Input the amout you with to subtract: ";
cin >> b;
c = a - b;
cout << a << " minus " << b << " equals " << c << ".";
cin.ignore(80,'\n');
cin.get();
}
void multi() {
float a;
float b;
float c;
cout << "Input a number: ";
cin >> a;
cout << "Input a second number: ";
cin >> b;
c = a * b;
cout << a << " times " << b << " equals " << c << ".";
cin.ignore(80,'\n');
cin.get();
}
void divi() {
float a;
float b;
float c;
cout << "Input a number: ";
cin >> a;
cout << "Input a second number: ";
cin >> b;
c = a / b;
cout << a << " divided by " << b << " equals " << c << ".";
cin.ignore(80,'\n');
cin.get();
}