What do you mean by a dry day?

Heavenly stems refer to the ten heavenly stems in heavenly stems and earthly branches.

Tiangan, an ancient Chinese character sequence symbol in China, contains 10 characters:? A, B, C, D, E, Ji, G, Xin, Ren and Gui are used circularly. China and other countries with Chinese cultural circles often used them to name, sort and determine dates in ancient times.

Heavenly dryness began in Shang Dynasty at the latest. The obvious evidence is that the titles of business leaders are merchants, B, B, C, Yi Ding, Zhu Renhe and Zhu Gui. Officially naming these ten symbols as heavenly stems should be related to earthly branches: stems are trunk and branches are branches, and these two relative names should appear together. In Shang Dynasty, heavenly stems and earthly branches was used to record the sun, but heavenly stems and earthly branches used it later.

Extended data:

Heavenly Stems and Earthly Branches

They will be repeated when the day's dry training exceeds 10, and they will start to repeat when the local dry training exceeds 12. The combination of heavenly stems and earthly branches can reduce duplication and avoid confusion. In ancient China, a kind of zipper-like combination of stem and branch was adopted, in which one side of the chain teeth was a round sky stem and the other side was a round ground branch. Finally, we can find the least common multiple of the two, that is, 60 combinations, so there is a saying that a nail is equal to 60 years.

Tiangan is a decimal, which is convenient for intuitive calculation; The earthly branch is decimal, which has advantages in recording time and month; The combination of trunk and branch is sexagesimal, which is suitable for the situation that the interval (year) is close and cannot be confused. In ancient China, the combination of heavenly stems and earthly branches was flexibly used to represent year, month, day and time, so the so-called birthday appeared.

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