4. loops

# calculator that tests input and keeps adding for ever
action = input("Insert maths sign (+,-,*,/) = ");
num1 = int(input("please input number = "));
loop = 0;

# loop until a non number is entered
while loop == 0:
    numX = input("please input number (press enter to end)= ");

    # tests if a number was input
    if numX.isdigit():
        # does maths
        if action == "+":
            num1 = num1 + int(numX);
        elif action == "-":
            num1 = num1 - int(numX);
        elif action == "/":
            num1 = num1 / int(numX);
        elif action == "*":
            num1 = num1 * int(numX);
        else:
            # wrong input
            print("Need a correct maths sign (+,-,*,/)")
            loop = 1;
    else:
        loop = 1;
        print("=", num1);