Why are there not a few days in the perpetual calendar?

Some simple printed calendars do not show the number nine. But you can do the math yourself.

"Counting on Nine" is a traditional way for China to record time. Since the winter solstice, nine nines have been recorded every nine days.

Usually the first month after the winter solstice is the coldest day in a year, so there are also sayings of "it's cold in March", "it's cold in March" or "it's cold in September". The Chronicle of Liang Dynasty and Jingchu wrote: "The number of winter solstice days, 998 1 day is the end of cold." Count nine cold days, that is, from the winter solstice, count nine every nine days, and it will not be warm until the "99" of 81 days.

From the date of the winter solstice, China entered the cold weather that lasted for several years. Astronomical experts said that "the Ninth Five-Year Plan" is a more applicable solar term in northern China, especially in the middle and lower reaches of the Yellow River. From the day of the winter solstice, it enters the "number nine", commonly known as "cross nine", and then every nine days is a unit, called "nine". After nine "nines", it happens to be 8 1 day, that is, "nine out", and then spring blossoms.