Luhn algorithm

<p>The Luhn algorithm or Luhn formula, also known as the "<a href="/facts/Modular_arithmetic/0wtRa5dU">modulus</a> 10" or "mod 10" <a href="/facts/Algorithm/fnl5NmRt">algorithm</a>, named after its creator, <a href="/facts/IBM/QszA7nwd">IBM</a> scientist <a href="/facts/Hans_Peter_Luhn/j5zx9csm">Hans Peter Luhn</a>, is a simple <a href="/facts/Check_digit/qMlumJpU">check digit</a> formula used to validate a variety of identification numbers. It is described in <a href="/facts/United_States/P0sCdLe5">US</a> patent 2950048A, granted on 23 August 1960.
</p><p>The algorithm is in the <a href="/facts/Public_domain/YWKMDKw4">public domain</a> and is in wide use today. It is specified in <a href="/facts/ISO%2fIEC_7812-1/CRFtA7FF">ISO/IEC 7812-1</a>. It is not intended to be a <a href="/facts/Cryptographic_hash_function/cuxkgbST">cryptographically secure hash function</a>; it was designed to protect against accidental errors, not malicious attacks. Most <a href="/facts/Credit_card_number/g9C3edYe">credit card numbers</a> and many <a href="/facts/Government_identification_numbers/0frd2aya">government identification numbers</a> use the algorithm as a simple method of distinguishing valid numbers from mistyped or otherwise incorrect numbers.
</p>

Luhn algorithm open-in-new

Luhn algorithm