The check digit has no special meaning
It uses the first 12 digits and 2, 3, 4, 5, 6, 7, 8, 9, 2, 3 in sequence , 4, and 5 are multiplied together, the sum obtained by adding their products is divided by 11 and the remainder is obtained. When the remainder is equal to or greater than 10, it is represented by an X. For example: Patent No. ZL95115608. The remainder is 16, which is represented by X