C++:

//
// Created by malcolm on 2020-07-31.
//
// Advance Calculator

#include <iostream>
using namespace std;

int main(){
    int firstNum {0};
    int secNum {0};
    int maths {0};

    // Asking for two numbers
    cout << "Enter your first number\n";
    cin >> firstNum;
    cout << "Enter your second number\n";
    cin >> secNum;

    // Asking for operator
    cout << "What operator? (1: Addition 2: Subtraction 3: Multiplication 4: Divide 5: modulo)\n";
    cin >> maths;

    if(maths==1) {
        cout << firstNum + secNum << endl;
        return main();
    } else if (maths==2){
        cout << firstNum - secNum << endl;
        return main();
    } else if (maths==3){
        cout << firstNum * secNum << endl;
        return main();
    } else if (maths==4){
        cout << firstNum / secNum << endl;
        return main();
    } else if (maths==5){
        cout << firstNum % secNum << endl;
        return main();
    } else {
        cout << "Unknown Operator \n";
    }
    return main();
}