def sum_numbers(numbers):
    return sum(numbers)

def nums():
    numbers = []
    print("Enter numbers to add them up. If you want to stop, type 'n'.")
    while True:
        user_input = input("Enter a number: ")
        if user_input.lower() == 'n':  
            break
        try:
            numbers.append(float(user_input))
        except ValueError:
            print("Invalid. Please enter a valid number.")
    total = sum_numbers(numbers)
    print("The total sum of the numbers you entered is:", str(total))  
nums()