Define the concept of arithmetic, also known as integer "1". At present, there is no formal definition, only a descriptive definition widely existing in the practice of fraction teaching: putting a complete quantity (such as a distance, an item, a basket of apples, a book, a period of time, etc. ) or a number (positive number) as a whole or a unit, and gives the natural number 1. It can be written as "1". Mathematical significance 1. The unit of the original quantity (refers to the smaller quantity that constitutes the original quantity, such as the distance of 3 hours, and the average distance traveled per hour is the unit of distance. ) or the units of numbers can be converted into smaller units than "1". So there is the definition of fraction: divide unit one (or the whole "1") into several parts, that is to say, one part or several parts are fractions. ②. You can use "1" as the unit to redefine another quantity that is the same as the original quantity unit, and express it as a fraction. This score is often called the corresponding score of another quantity. Generally, ① the method of generating scores is called segmentation, ②.