1, the concept of number: number is a calculation method used to describe and measure the number of objects, which is more convenient for us to understand the number of objects.

2, the role of numbers: Numbers can be used to calculate the number of objects, such as several objects, thousands of objects and so on. It can also be used to express the value of a specific object, thus making financial transactions easier.

3. Basic concept of calculation: calculation refers to the process of solving problems with numbers. It includes computer, manual calculation, reasoning and other ways, and can be used to solve mathematical problems, scientific problems, financial problems and so on.

4. Operators: Operators are symbols used to represent specific mathematical operations. They include plus sign (+), minus sign (-), multiplication sign (×), division sign () and so on.