# Test Credit Card Numbers With Luhn Credit Card Validation

Published 7/11/08 (Modified 6/17/11)

By MoneyBlueBook

**What Do the Credit Card Numbers Mean, and How Are Valid Credit Card Accounts Generated?**

Have you ever wondered how credit card companies generate all those account numbers that appear on the face of the credit cards you carry around in your wallet? At first glance the numbers, while neatly arranged, appear to be completely random. But would it surprise you to know that there is indeed meaning and actual mathematical methodology to the way the numbers are sequenced? The process of generating real credit card numbers and validating them based on a proven mathematical formula is not only intriguing on an intellectual level and a hacker's dream, the carefully calculated way the numbers are ordered is actually quite beautiful and elegant when you come to understand how it works.

Before I get down to explaining the anatomy of credit card numbers and discussing how credit card numbers are generated, I think it's prudent to remind everyone the intent of this article. The goal of this blog post is not to encourage or get people thinking about how to go out and create fake credit card numbers on their own for improper means. The purpose is to shed some light on the science behind the mathematical sequencing technology of valid credit card numbers and offer some insight into something that many of us frequently see and use everyday, but oftentimes don't pay much attention to.

Please take in the information provided for purely academic and entertainment reasons. I'm not trying to encourage anyone to create fake credit card numbers and get themselves in trouble with the law. For anyone even thinking about engaging in fake credit card number hacking, keep this in mind - using mathematically generated credit card numbers to purchase products over the Internet or in real life is not only unethical and highly illegal, it's also not yet technologically possible (yet), based on the sheer probability of long shot odds of 1 in trillions. After reading everything I'm about to say carefully, you'll also realize that there is no realistic way to generate actual working credit card numbers that could be used for anything but entertainment reasons. The math and science behind generating authentic credit card numbers are only good for validation purposes and not sufficient for creating workable numbers as several highly encrypted numerical components are still needed. So, with that obligatory disclaimer out of the way, here is a short guide on how anyone can generate and verify the authenticity of any credit card number.

**Basic Background About Credit Card Numbers and How They Work **

Rather than ask you to take out a credit card out of your wallet to examine it, I've provided a picture of a prototypical card - in this case, it's a Visa credit card. While different card types offer different lengths of numerical digits, most major credit card issuers popular in the United States have 16 primary numbers on the front face of the card. Visa, MasterCard, and Discover cards all have 16 digits. American Express is the only major credit card issuer in the U.S. with one less number - at 15 digits. Regardless of the length of numbers, their numerical sequencing is still guided by the same Luhn validation formula, the mathematical check sum equation that makes all valid credit card numbers error free.

As you can see from the picture of the Visa card above, the very first 6 credit card number sequence is known as the issuer identification number (IIN) or bank identification number (BIN). These first 6 numerical digits denote the credit card network and the banking institution the card is a member of. The issuer identifier number also incorporates the card type's special identifying numerical prefix.

- All typical 16 digit Visa account credit card numbers start with a prefix of 4.
- All 16 digit MasterCard account numbers start with a prefix of 5.
- All 16 digit Discover account numbers start with a prefix of 6011.
- All 15 digit American Express credit card numbers start with a prefix of 37.

There is less randomization during this initial set of 6 digits as the numbers are determined purely by the card issuing source. Validation systems that want to go the extra mile in verifying authenticity oftentimes scan this first numerical sequence to match the known bank and issuing location of the card with the provided customer billing address for further validation accuracy.

The lone digit at the very right end of the complete 15 or 16 digit credit card number sequence is known as the "check digit", which often is the final number that is computer generated to satisfy the mathematical formulations of the Luhn check sum process. Meanwhile, in between the first 6 digits and the last single check digit is the actual personalized account number - the 8 or 9 digit sequence given by the card issuer. For more basic background information about credit card numbers, check out this credit card features **brochure** for more useful knowledge about the embossed and printed information found on your typical plastic credit card.

**What's The Secret Behind The Luhn Algorithm, Also Known As The "Modulus 10" Or "Mod-10" Formula?**

The Luhn Algorithm is the check sum formula used by payment verification systems and mathematicians to verify the sequential integrity of real credit card numbers. It's used to help bring order to seemingly random numbers and used to prevent erroneous credit card numbers from being cleared for use. The Luhn Algorithm is not used for straight credit card number generation from scratch, but rather utilized as a simple computational way to distinguish valid credit card numbers from random collections of numbers put together. The validation formula also works with most debit cards as well.

The Luhn formula was created and filed as a patent (now freely in the public domain) in 1954 by Hans Peter Luhn of IBM to detect numerical errors found in pre-existing and newly generated identification numbers. Since then, it's primary use has been in the area of check sum validation, made popular with its use to verify the validity of important sequences such as credit card numbers. Currently, almost all credit card numbers issued today are generated and verified using the Luhn Algorithm or Modulus, Mod-10 Formula. Needless to say, if you come upon some existing credit card numbers that fail the Luhn algorithm when put to the test, it is safe to assume that they are not valid or genuine numbers.

The one thing to keep in mind is that validity in terms of passing the Luhn test only means that it is mathematically valid for computational compliance purposes. It does not guarantee that the credit card number sequence is indeed a working number that is backed up with a valid credit card account on the card issuer's end. It is not unremarkable for one to artificially generate a mathematically valid credit card number that passes the Luhn validation check, but still ultimately fails as a fake credit card number with no actual substance. The Luhn algorithm only validates the 15-16 digit credit card number and not the other critical components of a genuine working credit card account such as the expiration date and the commonly used Card Verification Value (**CVV**) and Card Verification Code (CVC) numbers (used to prove physical possession of the debit or credit card).

**The Nerdy Process Of Applying The Luhn Algorithm To The Creation and Validation Of Credit Card Number Sequences**

For those who hate math or get scared when they encounter a bunch of scary looking mathematical formulas and numerically inspired descriptions, you are not alone. I personally hate math as an academic subject and was rather terrible at it back in high school and college, but if you like visual, thinking puzzles like Sudoku, you'll like working with the Luhn Algorithm. It's pretty clever and remarkably well put together. It's also pretty easy to explain.

- First, you'll need to lay out all 15 or 16 numerical digits of the credit or debit card number. The Luhn Algorithm always starts from right to left, beginning with the rightmost digit on the credit card face (the check digit). Starting with the check digit and moving left, double the value of every alternate digit. Non-doubled digits will remain the same. Remember that the check digit is never doubled. For example, if the credit card is a 16 digit Visa card, the check digit would be the rightmost 16th digit. Thus you would double the value of the 15th, 13th, 11th, 9th digits, and so on until all odd digits have been doubled. The even digits would be left the same.
- For any digit that becomes a two digit number of 10 or more when doubled, add the two digits together. For example, the digit 5 when doubled will become 10, which turns into a 1 (when 1 and 0 are added together). Likewise, the digit 9 when doubled will become 18, which becomes 9 (as 1 and 8 are added together). Obviously, 0 when doubled will remain 0.
- Now, lay out the new sequence of numbers. The new doubled digits will replace the old digits. Non-doubled digits will remain the same. Thus, you should be able to come up with a new sequence of 15 or 16 numerical digits depending on card type.
- Add up the new sequence of numbers together to get a sum total. If the combined tally is perfectly divisible by ten (ends in 0, like 60 for example), then the account number is mathematically valid according to the Luhn formula. If not, the credit card number provided is not valid and thus fake or improperly generated.

**An Example Of the Luhn Validation Technique In Action - Using Homemade Graphics **

For the visual types like myself, let's use the American Express credit card on the right to better demonstrate the doubling and addition mathematics of the Luhn Algorithm. Follow the numbers and you'll realize that it's not as difficult as it may first appear. It's actually very easy once you get the hang of it. You won't look at credit card numbers the same way ever again after you get a good grip of it - I assure you. You'll find yourself testing credit card numbers for fun!

Ignoring the obvious Amex logo on the card, right of the bat it's clear the account number is that of an American Express number - denoted by the numerical prefix - "37". Now let's crunch the numbers through the Luhn Algorithm using the following displayed Amex credit card number: 3759-876543-21001. It doesn't matter if the credit card number sequence has 15 numbers like the American Express or 16 numbers like Visa, MasterCard, or Discover, the Luhn validation check should be able to verify whether this card number is a mathematically authentic credit card number regardless. Follow the Luhn steps from #1 to #4 below, starting with the rightmost check digit.

In this case, the total calculated sum was 57, which is not divisible by 10 (the added up sum does not end with zero). Thus the number fails the Luhn Algorithm validation check. According to the Luhn test, this particular Amex credit card number is completely bogus and fake. The numbers were likely randomly slapped together. To make this particular set of numbers Luhn compliant and error free, all we would have to do is change the all important "check digit" number from 1 to a 4, which would result in a total sum of 60, thereby becoming Luhn compliant.

If you want to test this mathematical theory out in real life, I recommend pulling out your own credit cards and spending a few seconds to run a quick Luhn screening on them just for your own amusement and education. Pretty neat isn't it? If you want another credit card number to test on, try using the credit card number that is displayed on the cartoon "VIZA Card" [sic] that Bart Simpson is holding up in the graphic at the top right of this article - the card is in the name of "Rod Flanders", and the credit card number is: 8525-4941-2525-4158. Tip: Just by looking at the prefix numbers you probably should already be able to tell that the account number's completely random and fake.

**Use The Luhn Formula To Validate Existing Accounts But Don't Attempt To Create and Use Fake Credit Card Numbers **

Now with this new found knowledge, keep in mind you still won't be able to randomly generate genuine workable credit card numbers. The Luhn theory only allows you to generate mathematically compliant credit card test numbers, not hack workable ones. Besides, without valid expiration dates, and valid CVV2, CVC2, or CID numbers (the special security codes printed on the back or front of credit cards as additional authentication measures), you still wouldn't be able to legitimately use your self generated numbers to run credit transactions anyway.

Cracking and hacking the security codes found on credit cards is currently impossible. To calculate a workable 3 digit CVV2 security code, the algorithm requires a primary account number (PAN), the 4 digit expiration date, a special 3 digit service code, and a pair of DES keys. With such heavy encryption and billions to trillions of numerical possibilities, unless you have God-like mental processing power and a fleet of super computers at your disposal, you won't be able to use brute force guessing attempts to crack the codes.

While it's good to use this type of information to education yourself on the inner workings of credit cards and mathematical validation theory, it's best to stay away from trying to further crack the secret of credit card codes to come up with free workable account numbers. Don't use the Luhn Algorithm for anything else but personal entertainment and amusement.���� Please don't go around trying to generate a list of fake credit card numbers on your own and trying to buy stuff with them. I know some of you out there may be tempted to try, but you'll just get yourself in trouble.

June 11, 2009 at 8:13 pmHi,it is high time we know who is the don in the damn website, if you know you want to campaign,send credit card to this email for ranking and rating, i did not need your creditcard,it is just good to know who is the head

June 19, 2009 at 3:56 pmHey guys,

i was wondering

if you guys can send me

two or 1 VALID CC's that work.. with the valid information!please

im begging,thanks alot!……………

much love

June 19, 2009 at 8:34 pmDudes,you Guys `ve got lotes of unrealistic dreams.How on earth do you Guys think that someone is gonna send you a valid CC`s and details.I`m not convinced,can any one prove to metaht he`s got a valid CC`s right here??????

June 20, 2009 at 12:43 amcan i have a valid master card credit card number im begging u guys i want it so bad i will thank u alot if it works

June 27, 2009 at 8:37 pmWhat is the matter with all of you????? I do not have the least nit of sympathy for those who are trying to steal credit card information. Instead of begging for people to give away credit card infomation.....get of your lazy ass and go to school, get a degree, and find a job that will enable you to live a wealthy life. Just stop all of this nonsense please.

June 29, 2009 at 7:36 pmman i just wann 20 $ u hear mee!!! u hear me !! i wanna 2o $ just 20 $

June 30, 2009 at 9:29 amI am inviting all other bad boys that are interested in hacking,generating creditcard,this site is too dull for my liking, no stuffs, no any orientation. we are not hot.if you are interested add me to your messenger list and invite me so we can create a site that will be protected and we can distribute stuffs and hack creditcard

July 3, 2009 at 6:19 amIF I DONT GET A VALID VISA CARD I WILL REALLY DIE.................... LONG STORY I HAVE 3 DAYS UNTELL I DIE IF I DONT GET A VALID CARD NUMBER!!!!! MY LIFE IS IN YOUR HANDS!! SO PLZ PLZ PLZ E-MAIL ME

July 4, 2009 at 5:29 amBishop,

Thank you for putting your life in my hands so eloquently, but unfortunately in your case, you may just have to kick the bucket and leave this world without a valid VISA credit card. I do not have any real or fake credit card numbers to give out despite information to the contrary as reflected in the persistent blog comment solicitations for credit card numbers.

My advice is to please stop being so dramatic. If you want an actual card number, why not just go and apply for a legitimate account rather than begging for a free credit card handout?

July 6, 2009 at 5:48 pmpls send me an email to no how the site works and how to make a requuest

July 8, 2009 at 2:15 amits really hard to create dumps and long numbers for a credit cards i have been working on it for years.you need programming and some stuff and u need to seperate them with formulas...I CAN WRITE DUMPS AND PRINT THEM ON DESIGNED CARDS - PREPAID CARDS..for more informations please send me an email

July 10, 2009 at 8:08 ami need a valid master card for my study pls

July 10, 2009 at 3:38 pmmy names are stanley timjek i have been hearing about your site that you give out valid cc to those who are in need of it please i will like you to help me with a valid master or visa card with cvv no and all the necesary information required i will be very greatful if my requet is been granted thanks for your co oprate. please reply back as soon as you get my message.

July 10, 2009 at 4:36 pmWhy don't you block all IP's from the countries that are spamming you. Better yet, redirect them to a site that will load their computers with viruses as I'm sure those beggers don't know what an anti-virus engine is or how to keep it current.

If anybody is actually smart enough to crack that formula and produce numbers, then they wouldn't be begging as I'm sure somebody would be willing to pay them a huge salary for legitimate work.

Thanks for the info on learning what makes something valid or not, helps with validation I'm working on.

July 14, 2009 at 11:31 pmHello Fresh, and Anyone who can help me with bank Transfer or westernunion transfers pls contact me

I SERIOUSLY NEED SOMEONE WHO CAN HELP ME WITH EITHER CREDIT CARD, BANK AND WESTERNUNION TRANSFERS, KINDLY CONTACT ME.

MURPHY.

July 15, 2009 at 4:15 amHi can I also get a valid information and a valid credit card for doing survey

July 15, 2009 at 5:38 pmYou Guys had better wake up from your Dreams!!!!!!!!!!!!!!!!!!!!LOL!!

July 17, 2009 at 10:06 amdid any of you even read the topic!? i mean, seriously!

July 17, 2009 at 2:55 pmTo whom it may concern

Requesting a donation as unhappiest Tamil man in sri lanka

I wish to make an appeal to our community who lives world over to listen to my sad life story and help me and my two innocent children to live.

I am Mr.Vardharaja Perumal of vavniya in sri lanka, was living with my wife Mrs.dharshani Perumal and two daughters Miss.Diwya 8 years Miss.Bhanu 4 years in vavniya till December 2006.War situation was start again and in order to make some living I and my family came to horana. I bought a house and worked in a bakery and my wife worked in a privet rubber factory. But due to kidney failure of my wife, I had to mortgage our house to a money lender for some of rupees 1.2 million and I tried to rescue of my wife and the mother of my two daughters ; but my efforts were lost as she scarified for a long period and passed away by keeping a impossible liability ahead of mine.

As I have no any relation to help because the war loosed everything from us. I am lost to understand as how to and which precautious I should take to release my house from the money lender and how to make the two children educational and livings.

As the interest of my house mortgage has arisen areas; I was asked to handover the house and leave. But Oh .god where am I to go: with my two children. We are a small community people who get harassed and if I don't get any help from there sinhala community people. I have no option other than succeeding with my children.

I very humbly and sincerely request the very kind people to help me by contributing some money in possible manner to get establish in our own house by releasing the faced to the money lender which will be a very great help for my family in this junction.

Here with I am forwarding my e-mail address and Paypal account for your very kind references; and may I request you to contribute at least 10 $ if possible put it in to may pay pal account(One of a Student in Horana call S.pttiyage,Help me to these things I haven't phone you can contact him *deleted by editor*)

My Mail: (deleted by editor)

Paypal Account : (deleted by editor)

May I pray you all very prosperous and healthy life in future.

You're sincerely,

Vardharaja Perumal

July 17, 2009 at 3:07 pmSorry Mr. so-called "Vardharaja Perumal of Vavniya in Sri Lanka...if that is your real name.

Looks like you'll just have to suffer a terrible financial death with your two supposed children. No one has any pity on you so please just go to a small corner somewhere or have some one put you out of your supposed misery.

Please stop scamming people. I did a Google search and you've been posting the same message on various blogs. Get lost.