How many hours are there from 9: 00 yesterday morning to 9: 00 this morning?

According to the Gregorian calendar, 9 am is Shi Si time, while according to the current 24-hour system, it is now 9 am to 1 1 in Shi Si. In ancient times, it was also called the horn, representing the time near noon.

As the first prime time for work and study, Shi Si is the most efficient time for office workers to study and work. Because the brain is the most active period during this period, solving important problems can be completed during this period.

9: 00 a.m. to 1 1 a.m. is the fourth time. A day is divided into twelve hours: Zi, Ugly, Yin, Mao, Chen, Si, Wu, Wei and Shen.

In ancient China, besides time, there were hundreds of minutes, mainly because time could only be tried during the day when the weather was fine, but it could not be used at night or on cloudy days.

In the long river of historical development, the engraving system has been developing continuously. By the early years of the Qing Dynasty, the government officially stipulated that it was 96 minutes per day, 8 minutes per hour and 15 minutes per hour. At this time, the "one moment" clock that lasted for thousands of years has finally changed from the initial 14 minutes and 24 seconds to today's 15 minutes.

The corresponding 24-hour time is: 19: 00 -2 1: 00 for the first shift, 2 1: 00 -23: 00 for the second shift, 23: 00-1: 00 for the third shift, and 23: 00 for the third shift.