The advantage of scientific notation is that it is easy to read and write, and sometimes it can display important numbers.

When the density is in international units, it is customary to record it as a× 10? kg/m？ This is a special counting method. For example, the density of water is 1.0× 10? kg/m？ The density of alcohol is 0.8× 10? kg/m？ Is the density of gold 19.3× 10? kg/m？ For solids and liquids, gases still use traditional notation, for example, is the density of air 1.29kg/m? . Moreover, if international units are not used, traditional notation, such as density and a common unit g/cm, is usually used. Is the density of water 1.0g/cm? Is the density of alcohol 0.8g/cm? Is the density of gold 19.3g/cm? .

As I said just now, this counting is just a habit, without which there is no way to do it. For example, someone recorded the alcohol density as 800kg/m? Or 8× 10? kg/m？ , also can't say wrong. But it's best to follow the habit and avoid unnecessary trouble. At the same time, I also remind you that you must look carefully, and you can't think that it must be a× 10? , related problems, will be 8× 10? kg/m？ As 8× 10？ kg/m？ The lessons of the past are not without.

Of course, the density of solids and liquids is a× 10? kg/m？ To a certain extent, it also embodies the advantages of simple reading and writing of scientific notation, which makes writing more standardized and the relationship between size more intuitive. Besides, kg/m? Use another common unit g/cm? (t/m？ 、kg/dm？ ) Is it 10? The conversion is very convenient.

Finally, by the way, the specific heat capacity is also recorded as a× 10? J/(kg℃), or a× 10? j/(kg·K).

Excuse me, what is mathematical counting? I don't know. Thank you for inviting me!

The writing of density does not necessarily follow the scientific counting method.

First of all, scientific counting exists only to make writing more convenient and concise.

For example, the density of alcohol is 0.8× 10? Kilogram/meter? This is a conventional writing method, not a scientific counting method. If scientific counting method is adopted, it should be written as 8× 10? Kilogram/meter? The alcohol density is 0.8× 10? Kilogram/meter? Can you also write 800 kg/m?

However, in formal occasions such as examination rooms, scientific counting should be used as far as possible.

This comes uninvited. Let me answer it.

First of all, the scientific counting method exists only to make writing more convenient, concise and easy to read, but the writing of density does not necessarily follow the scientific counting method completely.

If the alcohol density is 0.8× 10? Kilogram/meter? And the scientific counting method should be written as 8× 10? Kilogram/meter? Then why are they all written as 0.8× 10? Kilogram/meter? And rarely written as 8× 10? Kilogram/meter? And then what? Then it is necessary to find out the origin of scientific counting methods. It is believed that the scientific counting method was first used by an Indian, and it is said that it was invented by an unknown mathematician in India.

There was a great scholar in ancient Greece who counted "the amount of sand full of the universe", that is Archimedes. He wrote a paper called "The Method of Counting Sand". In this article, his counting method is very similar to the method of expressing large numbers in modern mathematics. He started with the largest digital unit in ancient Greece "Wan" and introduced a new number "Wan (100 million)" as the second unit.

At the same time as Archimedes, an astronomer named Aristakes calculated that the distance from the earth to the celestial sphere was100000000 stadim (1stadim =188 meters), which is of course much smaller than the universe we know now. This is just the distance from the sun to Saturn. Archimedes assumed that the "universe" was full of sand. Then he began to count the amount of sand. Finally, he wrote: "It is obvious that the number of sand grains that can be loaded in the celestial sphere calculated by Aristakes will not exceed10 million eighth-order units." If you want to write down the number of sand, it is 65,438+00,000,000× (65,000× 000) 7 or you should write it in 1: 1, 000,000,000,000,000,000,000,000,000.

In density measurement, there were many books in Europe at that time, but the reading method in Britain was to read them every three places, such as 000( 10? ) is thousands; And 000000( 10? ) is millions (millions); And 0 million (10? ) is billion (one billion); And so on. At that time, Britain was quite good at X, and most countries were using this technology and standard, so we continued to use 10? , 10? , 10? The interval is 3.

The expression of density follows the scientific counting method. It's just that the range of density expression that primary and secondary schools can reach is not large. You don't have to use scientific counting methods to express it completely.

The density of water is 1. Compared with the density labels of other solids and liquids, it is convenient to intuitively grasp the weight and volume characteristics of objects.