Here is a fun trick to entertain your buddies and win bar bets: Guess the initial digit on a credit card that's stashed in a wallet.

You're free to employ this method because **credit card numbers** aren't generated at random. The Luhn algorithm and MIIs, both of which seem like they belong in a spy book, may be used to decode a credit card number and determine whether or not it is legitimate or not.

This is because the International Organization for Standardization (ISO) has specified patterns for credit card numbers. Credit card numbers are more than just a way of identifying your account.

**The First Digit**

In credit cards, the first three digits are like the area code. Instead of 212 for New York City, it indicates an industry type, such as 4 for a financial institution. The MII or Major Industry Identifier is the first three or six digits of a credit card number issued by a large American bank.

Visa V, -0.85 percent cards always begin with a 4, while MasterCard MA, -1.00 percent cards typically begin with a 5. However, in 2017, **MasterCard** MA, -1.00 percent, began issuing some numbers starting with 2, while Visa V, -0.85 percent, started giving cards with numbers beginning with 2.

In the United States, the following is a list of the top card issuers:

- The First digit is 2; MasterCard is the card issuer.
- American Express AXP, -0.42 percent, is the first digit of the credit card number.
- Visa is the credit card company that issued the four-digit security code.
- The First digit is 5; MasterCard is the card issuer.

The rest of the numbers are used for other forms of identification. Banks issue airline credit cards; hence, numbers 1 and 2 belong to banks. The number 7 belongs to oil corporations, the number 8 belongs to telecoms, and the number 9 belongs to national numbering systems.

**The Middle Numbers**

An issuer identification number (IIN) is a six-digit number that begins with the first digit MII, commonly referred to as a bank identification number. These details can identify a bank or financial institution.

A string of digits represents customers' accounts after their initials; however, this string is seldom identical to the person's actual bank account number.

**The Last Digits**

As part of the verification procedure for credit card numbers, the processor checks to see if the digits follow what is known as the Luhn algorithm. The number is invalid if they don't. Hence, it is named "check digit" since it completes the procedure, divisible by 10 in the string of digits.

If you mistyped your credit card information when making an online purchase, it could instantly discover the error. The Luhn algorithm, which uses basic math but is challenging to explain, may be used to examine your cards.

Visa, MasterCard, and Discover cards all have 16-digit numbers.

- Double every digit except the first digit, then write down the resultant series of integers.
- Make a total of the digits that you recorded. Adding a two-digit number requires first adding the two digits together. Adding the 1 and 4 to create five and then using that 5 in your total, for example, would be equivalent to multiplying a seven by 2.
- Please take a look at the final digit on your credit card and add it up (no doubling)
- Add up the two figures.

The card is legitimate if the outcome is zero. Using the same methods, start with the second digit if the card contains 15 numbers, such as an American Express card in the United States.

**"Guessing" Numbers**

You can now see how a party-trick routine of guessing the initial number of someone's secret credit card may be developed now that you understand the digits. Tell me what kind of card you have to predict the first number. For a Visa, the number of days will be 4. MasterCard, guess 5, and if that's incorrect, think two if it is.

Another option is to accept their guess for the last digit if they're prepared to provide you with the rest of the information. To figure out the Luhn algorithm, use an internet calculator like this one. However, it may not be enough to make you the center of attention during the party.

**What Is the Location of the Credit Card Security Code?**

The CVV, or card verification value, is a three- or four-digit number. A network payment processor determines where the CVV is located.

Because you'd need to have the card in your hands to figure out the CVV, it's an added layer of protection. When someone steals your credit card number and tries to buy something online, they will be unable to do so unless they also have your **CVV number**.

This code is also used when placing a phone order for pizza. The restaurant staff asks for the expiration date and the CVV after you offer the credit card information. If you're holding the credit card in your hand, the answer is obvious.