def get_validation_digit(number):
    """Calculates the validation digit for the given number."""
    weighted_sum = 0
    dvs = [4, 3, 6, 7, 8, 9, 2]
    number = str(number)

    for i in range(0, len(number)):
        weighted_sum = (int(number[-1 - i]) * dvs[i] + weighted_sum) % 10

    return (10 - weighted_sum) % 10