Air China’s friend card originally had 9 digits, but was recently upgraded to 12 digits. The last 9 digits are the original number, and the first three digits are 00x (x is a number between 0-9 calculated based on the original card number through a certain calculation method). You can check your current card number by logging on to Air China's official website or calling Air China customer service. one time. From now on, just press 12 digits for check-in.