Why does a perpetual calendar have 20% days?

If the solar terms are odd, the only twelve stars on duty yesterday will be used on the same day.

For example, on the day of beginning of spring (20 14), twelve satellites were responsible for yesterday's stars. This is to keep the stars on duty for two days in a row.

On the day of the panic, twelve satellites were on duty with yesterday's star set, which means that they were on duty for two consecutive days.

On the same day in Tomb-Sweeping Day, twelve satellites were on duty with Man Xing yesterday, which means Man Xing was on duty for two consecutive days.

In summer, twelve satellites are on duty with yesterday's dangerous stars. This is a dangerous star on duty for two days in a row.

On the day of the awning, twelve satellites were on duty with the full moon yesterday. This is an all-star duty for two consecutive days.

In summer, twelve satellites are on duty with yesterday's stars. This is the star duty for two consecutive days.

You said so. There are two successful days.

The rest of beginning of autumn, Bailu, Hanlu, beginning of winter, Daxue and Xiaohan were on duty for two consecutive days with yesterday's star on duty.