Implementation of Luhn Formula

Question

I was trying to implement the Luhn Formula in Python. Here is my code:

import sys


def luhn_check(number):
    if number.isdigit():
        last_digit = int(         


        

Answer 1

This is the most concise python formula for the Luhn test I have found:

def luhn(n):
    r = [int(ch) for ch in str(n)][::-1]
    return (sum(r[0::2]) + sum(sum(divmod(d*2,10)) for d in r[1::2])) % 10 == 0

The above function and other Luhn implementations (in different programming languages) are available in https://www.rosettacode.org/wiki/Luhn_test_of_credit_card_numbers .