1. Historically, mathematical circles at home and abroad have always had two views on whether 0 is a natural number: one thinks that 0 is a natural number, and the other thinks that 0 is not a natural number. Since the founding of the People's Republic of China, textbooks for primary and secondary schools in China have always stipulated that natural numbers do not include 0. Most foreign mathematicians stipulate that 0 is a natural number. In order to facilitate international communication, People's Republic of China (PRC) national standard (GB 3 100-3 102-93), quantity and unit (1 1-2.9) was promulgated in 1993. Therefore, in the revision of mathematics textbooks for primary and secondary schools in recent years, the researchers and compilers of the textbooks are all revised according to the above national standards. That is, there is no object, which is represented by 0. 0 is also a natural number. Whether "0" is included in natural numbers is controversial. Some people think that natural numbers are positive integers, that is, counting from 1; Others think that natural numbers are non-negative integers, that is, counting from 0. There is no consensus on this issue. However, in number theory, the former is often used; In set theory, the latter is often used. Primary and secondary school textbooks stipulate that 0 is a natural number.
2. From the concept of natural number, natural number is the symbol of the same characteristics of all equivalent finite sets. So 0 is a natural number.