What do you mean, 6.7, 6.8 is 69?

Spring hits six or nine heads: beginning of spring. Sixty-nine: the sixth nine days after the winter solstice. The so-called "September" means that the "winter solstice" is the 1 day of September 9, and the first day of June 9 is the 46th day from winter to the future (including the day of winter solstice). Beginning of spring is the third solar term after the winter solstice (winter solstice, slight cold and severe cold), which is generally a solar term of 15 days, so "beginning of spring" is the 45th day after the winter solstice (including the day after the winter solstice), so beginning of spring must be the day before June 9th, that is, "beginning of spring hits 69 heads".