1 will care about the length of 0. 1 and 0 have different meanings and connections in mathematics. For example, the meaning indicated by the leftmost scale 0 in the ruler is the starting point of measurement. 1 is a natural number and a positive integer, and 1 represents a natural number and an object. The beginning of the count. 10 can indicate that 0 can represent the starting point.

unit of length

Km is commonly known as "km", which means 1790. In May, a special committee composed of French scientists suggested that one fortieth of the total length of the earth meridian passing through Paris should be used as the unit of length-meter. 1km =1000 m =10000 decimeter = 100000 cm, starting from 1983, "1 m" is defined as "1"

The original standard 1 m is one twentieth of the length of the prime meridian. That is, one tenth of the distance from the south pole or the north pole to the equator. However, because it was later discovered that the earth was not a right sphere, the definition of "1m" was changed to the standard length of the international rice prototype made of platinum-iridium alloy. Later, with the popularization of laser, the definition of "meter" was changed to take the wavelength multiple of light wave as the standard.

However, due to the uncertainty principle, it is impossible for us to get accurate measurements of length and time at the same time. Therefore, in 1983, the international organization of weights and measures changed the definition of light speed to the length standard, and set the light speed at 299,792,458 m/s (whole).