Calculation method of lunar calendar

First of all, I copy and paste, and the algorithm is complicated. Maybe your colleague has a good mental arithmetic ability!

The method of calculating the lunar calendar date from the solar calendar date: the lunar calendar date is based on the full moon, and each new moon is the first day. The full moon is 15 (the 16th month) and the dark month is 29 (the 30th month). However, at present, the date of the solar calendar is usually used to express the time. If you want to convert the date of the solar calendar into the date of the lunar calendar, you can use the following two methods: one is to search the newly edited perpetual calendar, for example, what is the date of the lunar calendar on June 8, 1984? Open the perpetual calendar, 10 June is the eleventh lunar month, so it is inferred that June 8 is the ninth day of the ninth lunar month. Secondly, we can use the formula to calculate the lunar calendar date:

Suppose: the number of AD years-1977 (or1901) = 4q+r.

Then: Lunar date =14q+10.6 (r+1)+date ordinal of the year-29.5n.

(Note: in the formula, q, r and n are all natural numbers, r

For example: Lunar date1May 7, 994 is:

1994- 1977= 17=4×4+ 1

So q = 4, r = 1, so the seventh day of the fifth lunar month is:

14×4+ 10.6( 1+ 1)+(3 1+28+3 1+3 1+7)-29.5n

= 204.2-29.5 Newton

Then divide 204.2 by 29.5 to get the quotient 6...27.2, where 6 is the value of n and the remainder 27 is the 27th day of the lunar calendar.