The year of Gui You is one of the sixty years in the official calendar, which roughly corresponds to Gregorian calendar years such as 1873, 1933 and 1993 (60-year cycle). In the AD year, if the number of years is divided by more than 60 13, or the number of years is divided by 10, the remainder is 3, and the remainder after dividing by 12 is 1. All the years from beginning of spring in that year to beginning of spring in the following year are "Gui You years".
The so-called calendar year of trunks and branches means that trunks and branches are literally equivalent to trunks and branches. In ancient China, the sky was dominant and the earth was subordinate. The connection between heaven and stem is called heavenly stem, and the connection between earth and stem is called earthly branch. Together, it is called heavenly stems and earthly branches, or "dry branch" for short. There are ten heavenly stems, namely A, B, C, D, E, Ji, G, Xin, Ren and Gui, and twelve earthly branches, namely Zi, Ugly, Yin, Mao, Chen, Si, Wu, Wei, Shen, You, Xu and Hai. The ancients put them together in the order of Jiazi, Ugly B and Bingyin (that is, the sky turns six times and the earth turns five times, which is just a cycle). Sixty pairs from Jiazi to Guihai are called Jiazi. The ancient Chinese used these 60 pairs of branches to represent the serial numbers of year, month, day and time, and this is the chronology of branches.
Their arrangement is an orderly branching cycle (60 Jia Zi) as follows: Jia Zi B Ugly Bing Yin Ding Mao Ji Si Wei Xin You Jia Yi Hai Bing Zi Ding Ugly Mao Xin Si Ren Wu Ji Shen Jia Yi You Bing Xu, Ding Hai Wu Zi ugly Geng Yin Xin Mao Ren Chen Gui Si Wu Ji Ding You Wu Ji Hai Geng. This cycle is called "a nail", which means 60 years.