My calculator program keeps crashing at the end

[Azomb]

If you're looking for opinions, I'd suggest a separate function that gets the numbers, and passing those numbers to the add, multiply functions. Any time you're doing the same thing repeatedly, you should be using a function that you call.

Why do you have calls like
else
multiplyA();
in all operation functions?

You know the operation type in whateva. Just call the appropriate function after enterB.

I started learning like two days ago... It was the only way I could think of this working. And so it can respond with "Nice, what are you (adding/subtracting/multiplying/dividing) 5 by?"