The bank identification code, namely the BIN number, consists of six digits and is the header of the bank card number. The BIN number at the beginning of 4 is bought by VISA, and most of the ones at the beginning of 5 are bought by MasterCard. 6 China applied for it in 2002, which is an international standard bank identification code. The middle number is customized by the issuing bank and generally consists of 6- 12 digits. You can use at most 12 digits. Every bank has different rules for identifying individual account numbers. Some banks will include code information such as branches, sub-branches and savings outlets in this part.