How is the check digit of a Chinese application number calculated?

Answer:

The character after the decimal point is a check digit calculated from the application number.

Eight-digit application numbers

Represent the eight digits by a, b, c, d, e, f, g and h. Calculate 2a + 3b + 4c + 5d + 6e + 7f + 8g + 9h and divide the result by 11. The remainder is the check digit. A zero remainder gives 0; a remainder of 10 is represented by X.

For 98900001.X, the calculation is (2×9 + 3×8 + 4×9 + 5×0 + 6×0 + 7×0 + 8×0 + 9×1) ÷ 11. The remainder is 10, so the check digit is X.

Twelve-digit application numbers

Represent the twelve digits by a through l. Calculate 2a + 3b + 4c + 5d + 6e + 7f + 8g + 9h + 2i + 3j + 4k + 5l and divide by 11. Again, the remainder is the check digit, with 0 for a zero remainder and X for 10.

For 200610045875.9, the calculation is (2×2 + 3×0 + 4×0 + 5×6 + 6×1 + 7×0 + 8×0 + 9×4 + 2×5 + 3×8 + 4×7 + 5×5) ÷ 11. The remainder is 9, so the check digit is 9.

Searching by application number

When using the SIPO English-language patent search system described in the original article (http://59.151.93.237/sipo_EN/search/tabSearch.do?method=init), omit the decimal point and check digit. Entering them prevents the system from finding the corresponding application.