Generating a valid bank account number requires following strict rules set by banks and financial institutions in various countries, which usually involve the following key points： --- ### **1. National/regional standards** The structure of bank account numbers in different countries varies greatly, and common rules include： -**IBAN (international bank account number)**: Used for international transfers, including country code, check digit, bank code and account number (e.g.: `DE89 3704 0044 0532 0130 00`). -**United States**: Usually 9-12 digits, may contain bank routing number (ABA) and account number. -**China**: The debit card number is usually 16-19 digits, and the first 6 digits are the identity of the issuing bank (for example, 622848 starts with ABC). -**European Union**: IBAN unified standard, the length varies from country to country (such as 27 digits in France and 22 digits in Germany). --- ### **2. Verification mechanism** Bank account numbers usually contain check digits (such as the Luhn algorithm) to detect input errors： -**Luhn algorithm**: Widely used in credit cards and some account numbers (such as American Express). -Example: The check digit is generated by mathematical calculation, if the account number is`7992739871? `, then the parity bit`? =3`. -**IBAN verification**: Verify the overall validity through modulo 97 operation. --- ### **3. Internal bank rules** -**Institution code**: The first few digits usually identify the bank or branch (such as the first 6 digits of China Unionpay card). -**Account type**: It is possible to distinguish savings accounts, public accounts, etc. by a specific number of digits. -**Randomness**: Part of the user's account number is randomly generated by the bank to ensure uniqueness. --- ### **4. Compliance and safety** -**Prohibited behaviors**: It may be illegal to generate your own account (such as forgery or fraudulent use). -**Legal means**: The real account number needs to be obtained through the bank account opening process (such as identity verification, KYC). --- ### **5. Sample tool (learning only)** -**IBAN generator**: Can generate fake IBAN that conforms to the format (such as [iban.com ](https://www.iban.com/structure ) of the sample tool). -**Luhn algorithm tool**: Verify the validity of the card number (such as [online Luhn calculator] (https://www.dcode.fr/luhn-algorithm )). --- ###**Important reminder** -**Forgery is strictly prohibited**: The generation of a real and usable account number must go through a legal banking process. -**Test purpose**: When developing a payment system, use the test account provided by the bank (such as PayPal's sandbox environment). For country-specific rules, it is recommended to consult the official documents of the local central bank or banking association.