1, prime number:

Prime numbers are also called prime numbers. A natural number greater than 1 is called a prime number, except for 1 and itself, which cannot be divisible by other natural numbers. The number of prime numbers is infinite. There is a classic proof in Euclid's Elements of Geometry. It uses ordinary methods to prove absurdity.

2. Factors:

Factor means that the quotient of the integer A divided by the integer b(b≠0) is exactly an integer with no remainder, so people say that B is the factor of A. In elementary school mathematics, two positive integers are multiplied, so both numbers are called the factor of product, or the divisor.

3. Composite number:

A composite number is an integer greater than 1 and can be divisible by other numbers (except 0) except 1 and itself. In contrast, it is a prime number, and 1 is neither a prime number nor a composite number. The smallest composite number is 4. Among them, the perfect number and the number of blind dates are based on this.

Extended data:

Properties of prime numbers:

1 and prime number p have only two divisors: 1 and p.

2. Basic theorem of elementary mathematics: Any natural number greater than 1 is either a prime number itself or can be decomposed into the product of several prime numbers, and this decomposition is unique.

The number of prime numbers is infinite.

4. If the prime number p is the largest prime number not exceeding n, then \ frac {n} {2} ">.

5. Among all prime numbers greater than 10, the unit number is only 1, 3, 7, 9.

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