Python: Get 1 by n Cycle Length

def get_cycle_len(num):
    found_remainders = [0] * num
    value = 1
    position = 0

    while not found_remainders[value] and value:
        found_remainders[value] = position
        value *= 10
        value %= num
        position += 1

    return 0 if not value else position - found_remainders[value]