Progressive Payment Solutions

What Do the Numbers On a Credit Card Mean?

Unlocking the mystery of credit card numbers can help you solve payment issues and help prevent credit card fraud.

We likely use them every day: tapping, swiping, or dipping our credit cards without giving their numbers another thought.

Yet, the numbers on the card each have an important role. They all play their part together in order to make payments fast and easy. So by understanding what they mean, you can both satisfy your curiosity and know how to solve potential issues in the future.

Let’s dive right into it by decoding what the numbers mean.

The meaning of credit card numbers

We’re used to strings of numbers in our daily lives: employee numbers, social security numbers, etc. 

But believe it or not, credit card numbers aren’t just a random string of digits that’s assigned to you. In fact, each number has a meaning behind it and needs to be in its proper place for the transaction to work. 

Let’s start at the beginning of this series of numbers to understand what they all mean when you put them together.

1st number: This initial number is known in the credit card industry as the Major Industry Identifier, or MII for short. It is there for a very important reason: this number tells you which credit card network the card is affiliated with. 

As you will see in our article on understanding how credit card processing works, the credit card transaction involves various parties communicating with one another, including the issuing bank. Thus, it makes sense that this first digit identifies who that party is.

The type and even brand of issuer will have a unique number. For example, a 3 means it’s an American Express card, a 4 is a Visa card, 5 for a Mastercard card, and 6 is for Discover cards. However, there are other numbers associated with airlines, retailers, banks, gas stations, etc. 

Let’s take a full look at what the first (MII) number will indicate about the card:

  1. Airline
  2. Airline & Financial
  3. Travel & Entertainment (AMEX)
  4. Banking & Financial (VISA)
  5. Banking & Financial (Mastercard)
  6. Banking & Merchandise (Discover)
  7. Petroleum
  8. Health Care & Telecommunications
  9. Open for Assignment  

2nd number-6th number: These numbers are actually connected with the first number. All together they form the Bank Identification Number, or MII, also known as the Issuer Identification Number, or BIN. This group of numbers further clarifies which credit card company issued the card.

7th number-15th number (or possibly 18th number, depending on the account): From here, these numbers are there to identify the cardholder’s specific account–they are all unique, unlike the first six. They also help with routing information to the proper channels during a payment.

Last number: This last digit is also known as a check digit. It’s there to make sure all of the card’s numbers are authentic via a special algorithm called the Luhn Algorithm.

This algorithm is used to determine the validity of many important numbers, including government IDs and IMEI numbers. Within this algorithm, each number on the credit card follows a certain pattern. So if even one single digit doesn’t follow it, the credit card number is flagged as invalid and the transaction doesn’t go through. 

However, there’s more to credit card security than the last digit. Find out how to understand the security codes next.

Understand the credit card security code

Even though these 16-18 digits are unfakable thanks to the Luhn Altgorithm, they can still be easy to use by someone other than the account holder. That’s why additional codes are included to increase the level of security.

These security codes are called the Card Verification Value, or CVV. If it’s a Visa, Mastercard, or Discover credit card, this will be a three-digit code. If it’s an American Express card, it will be four digits. 

How, though, can you use this information to your business’ advantage? Let’s take a look at that next.

Credit card number tips

Since this string of digits is by no means random, you can actually use it to prevent fraud.

Avoid fraud by doing a little math.

For example, let’s say your network isn’t working–something we addressed in our blog on how to accept payments if credit card machines are down. You might need to manually enter a credit card number later when the network is back up.

So how do you know if it’s a legit number? Let’s look at six steps:

  1. Starting with the first number, double every other number. 
  2. Look at any double-digit numbers that result from this and separate them. For example, if one of the digits was a 6, then that will produce 12–so separate them into a 1 and a 2.
  3. Calculate the sum of all of the second (doubled) set of numbers
  4. Calculate the sum of all of the first (non-doubled) set of numbers
  5. Add these two numbers together
  6. Divide this number by 10

The end result should always be 0. If it’s not, you have a fraudulent credit card number. 

While it sounds complicated, it’s really not hard with a credit card in front of you–it can easily be achieved in around a minute with your smart phone’s calculator.

Credit card number best practices

If you are in this situation, it’s important to keep a few matters in mind.

The first is that you should always avoid writing down the entire credit card number. This is the same reason that receipts only show the last four digits: it prevents thieves from having what they need to use these numbers for fraudulent purchases.

Another tip is when in doubt, always report lost or stolen credit cards immediately. Some may hesitate to carry this step out because they think it takes too much time. However, credit card companies make this easy–all you need to do is call the number and list off the digits. 

Others think about the hassle of having to wait to get a new card. However, it’s a much greater bother to have to go through your statement line-by-line with the credit card company, explaining which transaction was yours and which was fraudulent–especially compared to having to wait a few days for a replacement card in the mail.


While credit card numbers may initially seem unintelligible, they are actually a very logical, organized group of numbers that ensure payment information is quickly and securely sent to the various parties involved.

Progressive Payment Solutions knows about everything and anything payment related–including how to save you both money and hassle with processing credit card payments. Contact us today to discover the difference we can make for your business.

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