Why do some bank card numbers have 16 digits and some have 19 digits?

Do you know what the numbers on your ID card represent? (See the answer at the end of the article)

There are many places where numbers are used in life, such as ID card number, phone number, bank card number, postal code, book number, etc. These numbers that seem to have no logic actually contain mysteries...

Take a bank card as an example and unravel the mystery of the numbers.

Bank cards are cards for storing wealth, and the long string of numbers on the card is equivalent to the "ID number" of the card. Because of the unique number authentication, this card can be officially circulated in the market and serve the public.

According to data from the National Bureau of Statistics, as of now, based on the population of my country, if each person holds 10 cards, banks need to issue approximately 14 billion cards. Therefore, in order to meet everyone's card needs, the number of characters on the bank card needs to reach 11 to ensure that each card is unique.

But if you look closely, you will find that our card numbers are usually much longer than 11 digits. The shortest ones are 16 digits, and the longest ones can be up to 18 or 19 digits. Why are these numbers so long, and what rules are contained in the numbers?

Issuing bank identification code

The first few digits of a bank card are also called the Bank Identification Number (BIN), which is usually composed of six digits. At the end of 2014, the International Organization for Standardization (ISO) adjusted the BIN from 6 digits to 8 digits.

1. Issuing bank logo

2.EMV chip

3. Holographic anti-counterfeiting image

4.16 or 19 digit card number

5. Trademarks of bank card issuing organizations

6. Validity period (MM/YY, usually 3-5 years)

7. Cardholder name

Image source: Wikipedia

Due to the large number of banks in my country and the growing size of village banks, although the 6-digit BIN length is dominant, 7-, 8-, 9-, and 10-digit identification codes are becoming more and more common.

From the first digit of the card issuer identification code, we can clearly understand the industry the card issuer is in. Different digital identifications represent different industries.

Currently, the standard for UnionPay cards is to start with 62, and there are only two cases where other numbers are used to start with it.

1. A co-branded card of two organizations, most of which are credit cards.

2. Bank cards starting with 9. These cards were issued in the early days of my country and are only for domestic use. They cannot be used for international financial transactions.

3. For people who use Visa credit cards in China, their card numbers will start with 4.

4. MasterCard card numbers usually start with 51, 52, 53, 54, or 55.

Identification of information in the identification code

Through the bank card identification code, we can not only obtain relevant information about the issuing bank, but also obtain the business category of the bank card.

UnionPay cards starting with 622848 are debit cards of the Agricultural Bank of China; cards starting with 622689 are credit cards of China CITIC Bank; and cards starting with 370285 are credit cards of China Merchants Bank. Therefore, as long as you obtain the identification code of the bank card, you can also obtain the corresponding information such as the issuing bank and card type. Currently, most mainstream applications that require card binding, such as Alipay and WeChat, are implemented in this way.

After the six-digit identification code, the seventh digit onwards is the personal account identification.

The personal account identification rules of each bank are different. Some banks will include code information such as branches, sub-branches, and savings outlets in this part, while some banks may directly use natural sequence codes. The numbers are randomly generated and have no special meaning.

Image source: hippopx

The last digit is the check digit. The Luhn algorithm (a simple checksum algorithm, generally used to verify identity codes) created by IBM scientist Hans Peter Luhn is used to calculate the last digit of the credit or debit card number by adding the digits preceding the card number.

The calculation method is as follows:

First, take the first number on the right as the starting number, and multiply every other digit by 2;

Next, add the value obtained in the first step to each digit, and then add it to each digit of the original number that has not been multiplied by 2;

Finally, find the 10's complement of the unit digit in the sum value in the second step. If the unit digit is 0, the check code is 0.

Interested friends can follow this formula to see if the last digit of their card number is consistent with the algorithm.

Bank cards are very important transaction tools. Once a bank card is assigned to a specific owner, the cardholder's relevant information will be transmitted to the central bank to prevent the cardholder from engaging in illegal financial transactions. While we do not do things that endanger financial security, we must also be careful to prevent bank card information from being stolen by others. In order to raise everyone's awareness of safety precautions, Tadpole Jun, the temporary spokesperson for the National Anti-Fraud APP, gives you some tips on safe card use!

Develop safe card usage habits

One of the main reasons for bank card fraud is the leakage of the cardholder's personal information or improper use of the card. In daily life, never lend your bank card to others, and pay attention to the surrounding environment when entering the password. Bank cards that are no longer used should not be discarded at will. The correct way is to cancel the account at the bank.

Protecting against dangerous information environments

While online payment brings convenience to production and life, it also comes with some risks. During the consumption process, we must protect the information security of financial account login, withdrawal and related verification codes, and not provide them to third parties. At the same time, be vigilant against unfamiliar calls or harassing calls, do not easily click on links or download corresponding software, and avoid registering personal information such as ID cards, bank cards, passwords, verification codes, etc. in unsafe network interfaces or network environments.

Image source: hippopx

With the development of the Internet, bank cards are slowly being replaced by mobile payments. But when you get paid every month, the happiness you get from seeing the growing numbers in your bank card is something that cannot be replaced by any other payment method. (Not really)

Here are the answers to the questions at the beginning of the article:

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