Calculate Digital Root of Number in Python

Enter number: 57
Digital Root: 3

def main():
    """
    Finds the digital root of a number in a given radix.
    """

    RADIX = 10

    num = int(input("Enter number: "))
    num = abs(num)
    root = 1 + (num - 1) % (RADIX - 1) if num != 0 else 0
    print(root)


if __name__ == "__main__":
    main()