Luhn Algorithm is a Modulus 10 and Mod 10 , is a simple checksum formulae used for validating a variety of identification numbers, such as credit card numbers, IMEI numbers and Canadian Social Insurance Numbers.

Let's supposed an example of a Debit / Credit Card number 4716 2495 3356 7731. First, seperate card number into seperation of array, then followed by double every second digit in the array.

Secondly, If the doubled value ishigher than 9, seperate those numbers into array and get the sum of both.

Now Override those values before 9 , to existing card number,

4 + 7 + 1 + 6 + 2 + 8 + 9 + 5 + 3 + 6 + 5 + 6 + 7 + 7 + 3 + 0 = 79

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\therefore This Card Is Not Valid:: Not A Multiple Of Ten