How to convert the chronology and chronology in ancient China?

I know the algorithm of chronology, but I can't do anything about age.

Calculation ×: divide ×-3 by 10 and 12 respectively, then calculate the remainder for ten days, and find out the words of the remainder with twelve branches.

Example: (March 2004) ÷ 10, and the remainder is 1.

(March 2004) ÷12, the remainder is 9.

Therefore, according to the order of ten days' work and twelve days' support, the year number of 2004 is: Shen Jianian.