1, natural number: natural number refers to numbers such as 1, 2, 3, 4, 5, 6, 7, etc ... It is one of the most basic concepts in mathematics and also the basis of the fourth grade olympiad.

2. Integer: Integer includes positive integer, 0 and negative integer, which is an extension of natural number.

3. Score: Score refers to the result that one number can be divisible by another number. It is composed of numerator and denominator, and it is one of the more important benchmark numbers in the four-level Olympic Games.

4.Decimal: Decimal refers to a number consisting of an integer part and a decimal part. The integer part to the left of the decimal point and the decimal part to the right of the decimal point are one of the more important benchmark numbers in the four-level Olympiad.

5.Percent: Percent refers to the percentage based on 100, which means that one number is expressed as the percentage of another number, and it is one of the more important benchmark numbers in the four-level Olympics.