When the winter solstice sets, it flies like a number.

When the winter solstice sets, a number is nine, because the winter solstice represents nine. Starting from the date of winter solstice, enter the number nine. Jiujiu is a folk solar term in winter in China.

In winter solstice, counting nine is a way for people to calculate solar terms. It was called Jiaojiu at first, and it was 19 every nine days, 19 in the first nine days, and 29 in the last nine days, and so on, until 99, that is, by the ninth nine days, the number reached 998 1.