Segmented timing method and 24-hour timing method;

A day starts at midnight 12, and the 24 hours of 1 day are divided into two sections, each of which is 12 hours. From 12 midnight to 12 noon is called the morning, and from 12 noon to 12 midnight is called the afternoon. This timing method is often used in life.

Twenty-four-hour timing method This is the timing method of 0 to 24 hours adopted by radio stations, stations, post offices and other departments. According to this timing method, 13: 00 in the afternoon, 2: 00 in the afternoon 14: 00 ... in the evening 12 is 24 o'clock and the next day is 0 o'clock.

Extended data:

Conversion relationship of time units:

(1) One day = 1440 minutes, 1 hour =60 minutes, 1 minute =60 seconds.

(2) A moment = 15 minutes, and a word =5 minutes (used in southern Fujian and Guangdong).

Angle relation of each pointer of the clock:

(1) An ordinary clock is equivalent to a circle, and its hour hand or minute hand is equivalent to walking 360 degrees.

(2) The angle of each large grid on the clock is 30.

(3) The angle of the hour hand every 1 min should be 0.5.

(4) The angle of minute hand per 1 min should be: 6.

Several key angles on the clock face:

Nine o'clock in the morning: the angle between the hour hand and the minute hand is 90 degrees.

Noon 12 o'clock: the angle between the hour hand and the minute hand is 0 degrees.

3 pm sharp: the angle between the hour hand and the minute hand is 90 degrees.

6 pm: The angle between the hour hand and the minute hand is 180 degrees.