What about the ID number of the Hong Kong ID card?

Hong Kong identity card number * * * six digits, plus the number in brackets * * * seven digits, preceded by English letter code.

The letters or numbers in brackets are actually used to verify whether the previous letters or numbers are misspelled.

The first seven digits of letters and numbers are given by weighted calculation, so the last digit is generally called the inspection number, which is used to check the accuracy of the first seven digits of the ID card, for example: Z 123456(7), Z 1234567(a).