number a is divisible by number b, a is called b times number, b is called a about number. Both about number and multiple number indicate the relationship between one number and another number, and cannot exist separately. For example, it can only be said that 16 is a multiple of a number and 2 is about a number, but it cannot be said that 16 is a multiple of a number and 2 is about a number in isolation.

" times "and" times number "are two different concepts," times "refers to two numbers divide the quotient, it can be an integer number, a small number or a point. "Multiple number" is only in the divisible range of number, as opposed to "about number", the concept of "one Number" means that it is divisible by some one Nature number, It has to be one Nature number.

several Nature numbers, public about number, called these several number convention number; one of the largest is called the number of the largest convention number. Example: 12, 16's convention number has 1, 2, 4, where the largest one is 4, 4 is 12, and 16's largest convention number is generally denoted as (12, 16) =4. 12, 15, 18's maximum convention number is 3, denoted as (12, 15, 18) =3.

Several Nature number public multiple number, called the number of the number common multiple number, the smallest one, called the number of the number of the number of the smallest one, called the number of the number of the number of the least common number. Example: The multiple number of 4's is 4, 8, 12, 16... 6's multiple number is 6, 12, 18, 24...... The common multiple of 4 and 6's has 12, 24,...... The smallest is 12, which is generally denoted as [4, 6]=12. 12, 15, 18's minimum common number is 180. Denoted as [12, 15, 18]=180.