The concept, definition and related knowledge of quantity
1, quantity is a mathematical concept, which represents the number of elements that make up a set. It is one of the most basic and primitive concepts in mathematics, which can be used to describe and measure various things, such as the number of objects, the number of events, the number of points in space and so on.
2. The definition of quantity can be understood from these aspects: the number of elements in a set: quantity can be regarded as the number of elements in a set. For example, there are 30 students in a class, so the number of students in this class is 30.
3. Measuring tool: Quantity can be used as a measuring tool to measure the quantity of various things. For example, the length, area and volume of an object can be measured by quantity.
4. Mathematical operations: Quantity can participate in mathematical operations, such as addition, subtraction, multiplication and division. For example, when finding the sum of a set of numbers, you can add up each number separately; When you find a multiple of a number, you can multiply the number by a multiple.
5. The essence of quantity is that quantity exists objectively: quantity exists objectively and does not depend on people's subjective consciousness. For example, the number of students in a class is objective and will not change because of people's subjective ideas.
6. Quantity is countable: quantity is countable, that is, elements in a set can be counted one by one. But some sets are uncountable, that is, all elements in the set are uncountable. Quantity has units: quantity has units, which can represent different characteristics of things. For example, one, ten, hundreds, thousands and so on. Can be used as a unit of quantity.
7. Quantity is directional: quantity is directional and can indicate the size and direction of things. Such as length, area, volume, etc. Can indicate the size and direction of quantity. Concept of number: The concept of number is the basis of quantity, including integer, fraction, decimal and so on. The concept of these numbers is one of the most basic concepts in mathematics.
8. Set theory: Set theory is a branch of mathematics, which mainly studies sets, their properties and operations. Measure theory: Measure theory is a branch of mathematics, which mainly studies the properties and operations of measurable set sum measure. Measure theory is widely used in mathematical analysis and probability theory.
9. Probability theory: Probability theory is a branch of mathematics, which mainly studies the calculation and derivation of random events and their probabilities. Probability theory is widely used in statistics, economics, biology and other fields.
10, mathematical statistics: mathematical statistics is a branch of mathematics, which mainly studies the methods and skills of data collection, collation and analysis. Mathematical statistics are widely used in social science, natural science, engineering technology and finance.