Luhn formulaBased on ANSI X4.13, the LUHN formula (also known as the modulus 10 -- or mod 10 -- algorithm ) is used to generate and/or validate and verify the accuracy of credit-card numbers.
Most credit cards contain a check digit, which is the digit at the end of the credit card number. The first part of the credit-card number identifies the type of credit card (Visa, MasterCard, American Express, etc.), and the middle digits identify the bank and customer.
To generate the check digit, the LUHN formula is applied to the number. To validate the credit-card number, the check digit is figured into the formula.
Here's how the algorithm works for verifying credit cards; the math is quite simple:
1) Starting with the second to last digit and moving left, double the value of all the alternating digits.
2) Starting from the left, take all the unaffected digits and add them to the results of all the individual digits from step 1. If the results from any of the numbers from step 1 are double digits, make sure to add the two numbers first (i.e. 18 would yield 1+8). Basically, your equation will look like a regular addition problem that adds every single digit.
3) The total from step 2 must end in zero for the credit-card number to be valid.
The LUHN formula was created in the late 1960s by a group of mathematicians. Shortly thereafter, credit card companies adopted it. Because the algorithm is in the public domain, it can be used by anyone.
The LUHN formula is also used to check Canadian Social Insurance Number (SIN) validity. In fact, the LUHN formula is widely used to generate the check digits of many different primary account numbers. Almost all institutions that create and require unique account or identification numbers use the Mod 10 algorithm.
Experts believe that Apple Pay and other competitive payment systems will be far more secure than cards, even cards equipped with EMV chips. Read More »Internet of Things Shaping IT's Future
To make the IoT both work and pay off, IT is juggling upgrading and building app-centric networks, mapping out new data center architectures and... Read More »What You Don't Read Can Hurt You
Does this sound familiar? An online service promises to help your small business cut costs, increase productivity, make your coffee and walk your... Read More »
The trend for the past two years has been for shoppers to spend more online during the holiday season. How do you typically shop for holiday... Read More »How to Create a Desktop Shortcut to a Website
This Webopedia guide will show you how to create a desktop shortcut to a website using Firefox, Chrome or Internet Explorer (IE). Read More »Flash Data Storage Vendor Trends
Although it is almost impossible to keep up with the pace of ongoing product releases, here are three recent highlights in the flash data storage... Read More »
Stay up to date on the latest developments in Internet terminology with a free weekly newsletter from Webopedia. Join to subscribe now.
- Watch Datamation's editor James Maguire moderate roundtable discussions with tech experts from companies such as Accenture, Dell, Blue Jeans Network, Microsoft and more »