Numbers: Numbers refer to writing numbers in a row side by side, and each number occupies a position. These positions are called numbers. Starting from the right end, the first place is the unit, the second place is the tenth place, the third place is the hundred places, the fourth place is the thousand places, and the fifth place is the ten thousand places, and so on. This shows that the concept of counting unit and number is different.

The generation of numbers: the origin of Arabic numerals: after the ancient Indians created Arabic numerals, they spread to the Arab region around the 7th century. By the 3rd century A.D./KLOC-0, the Italian mathematician Fibonacci wrote Abacus, in which he introduced Arabic numerals in detail. Later, these figures spread from the Arab region to Europe. Europeans only know that these numbers are imported from the Arab region, so they are called Arabic numbers. Later, these figures spread from Europe to all countries in the world.

Arabic numerals were introduced into China around 13 ~ 14 century. Because in ancient China, there was a number called "chip", which was convenient to write. At that time, Arabic numerals were not widely used in China. At the beginning of this century, with the absorption and introduction of foreign mathematical achievements by China, Arabic numerals began to be used slowly in China, and only now have they been popularized and used in China for more than 100 years. Arabic numerals have now become the most commonly used numbers in people's study, life and communication.

Natural number: a number used to measure the number of things or to indicate the order of things. That is, the numbers represented by the numbers 0, 1, 2, 3, 4, and ... the numbers representing the number of objects are called natural numbers, and they form an infinite group one by one from 0 (inclusive).

Calculation tools: abacus, calculator, computer.

Ray: In geometry, a figure formed by a point on a straight line and the part next to it is called a ray.