In the textbooks of nine-year compulsory education, it has been stipulated that "0" is a natural number. In the textbooks of nine-year compulsory education, "0" is listed as a natural number, and the smallest natural number is 0.
Natural numbers start from 0, such as 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,1,12, 13 and so on.
Extended data:
Natural number refers to the number of objects, that is, starting from 0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, etc. , forming one infinite group after another.
Note: Integers include natural numbers, so natural numbers must be integers and non-negative integers.
But the results of subtraction and division are not always natural numbers, so subtraction and division operations are not always true in natural number sets. 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, ... the numbers representing the number of objects are called natural numbers, and the natural numbers form an infinite group one after another.
There are addition and multiplication operations in the set of natural numbers. The result of addition or multiplication of two natural numbers is still a natural number, and subtraction or division can also be done, but the result of subtraction and division is not necessarily a natural number, so subtraction and division operations are not always effective in the set of natural numbers.
Two finite sets that can establish a one-to-one correspondence between elements have the same quantitative characteristics, which are called cardinality. In this way, all the single element sets {x}, {y}, {a} and {b} have the same cardinality, which is recorded as 1. Similarly, whenever two fingers can establish a one-to-one set, their cardinality is the same, recorded as 2, and so on. The addition and multiplication of natural numbers can be defined by ordinal number or cardinal number theory, and the operations under the two theories are consistent.
Natural numbers are integers (including positive integers and zeros), but not all integers are natural numbers. For example,-1 -2 -3 ... is an integer rather than a natural number. Natural numbers are infinite.
The set of all nonnegative integers is called the nonnegative integer set, that is, the natural number set.
When counting objects, the number of 1.2.3.4.5.6.7.8.9 is called a natural number. Natural numbers have two meanings: quantity and order, which are divided into cardinal number and ordinal number.
Basic unit: Counting unit: one, ten, one hundred, one thousand, ten thousand, one hundred thousand and so on.
Baidu Encyclopedia-Natural Numbers