How many days does it take to count to nine?

China has been in cold weather for several years since the winter of November. "Ninth Five-Year Plan" is a suitable solar term in northern China, especially in the middle and lower reaches of the Yellow River. From the day of winter solstice, it entered the "number nine", commonly known as "cross nine", and then every nine days as a unit, called "nine". After nine "nines", it is exactly eighty-one days, that is, "nine out", and then spring blossoms.