Factors and multiple prime numbers, composite numbers, odd numbers and even numbers
1.4×3= 12, 12 is a multiple of 4, 12 is also a multiple of 3, and 4 and 3 are both factors of 12.
Second, the smallest multiple of a number is itself, and there is no multiple. The multiple of a number is infinite.
3. The smallest factor is 1, and the smallest factor is yourself. The number of factors of a number is limited.
Multiply of 4.5: The number in the unit is 5 or 0.
Multiply of 2: The number in a unit is 2, 4, 6, 8 or 0. A multiple of 2 is an even number.
Multiply of 3: The sum of numbers must be a multiple of 3.
5. Numbers that are multiples of 2 are called even numbers. Numbers that are not multiples of 2 are called odd numbers.
6. A number is called a prime number if it has only 1 and its own two factors.
7. If a number has other factors besides 1 and itself, it is called a composite number.
8. In the number 1-20: (1 is neither prime nor composite)
Odd numbers: 1, 3,5,7,9, 1 1 3, 15, 17, 19.
Even numbers: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20.
Prime numbers: 2,3,5,7, 1 1, 13, 17, 19. (A total of eight, a total of 77. )
Complex numbers: 4,6,8,9, 10, 12, 14, 15, 16,18,20. (total 1 1, and the sum is 132. )
9. The smallest odd number is 1, the smallest even number is 0, the smallest prime number is 2, and the smallest composite number is 4.
10. If two numbers are multiples, the big number is the least common multiple and the decimal number is the common factor.
1 1. If two numbers only have the common factor of 1, then the common factor is 1, and the least common multiple is their product.