Calc

while True:
    a = input("NUMBER")
    class Calculator:
        def __init__(self):
            self.total = int(a)
        def add (self,num):
            self.total = self.total + num
        def sub(self,num):
            self.total = self.total - num
        def mult(self, num):
            self.total = self.total * num
        def div(self, num):
            self.total = self.total / num       
        def get_total(self):
            return self.total
    Calculator1 = Calculator()
    command = input("what type of arithmetic operation do you want?")
    if command == "add":
        Calculator1.add(int(input("Add with?")))
        print(Calculator1.get_total())
    elif command == "sub":
        Calculator1.sub(int(input("Sub by?")))
        print(Calculator1.get_total())
    elif command == "mult":
        Calculator1.mult(int(input("Mult with?")))
        print(Calculator1.get_total())
    elif command == "div":
        Calculator1.div(int(input("Div by?")))
        print(Calculator1.get_total())