The problems of sum and difference, sum multiple and difference multiple are the entry-level application problems of extracurricular expansion. Sum multiples and difference multiples are also collectively called multiples, which, as the name implies, is an application problem to study the relationship between multiples. Common in the second and third grade application problem expansion. It is a scientific strategy to teach junior students to recite quantitative relation formulas to solve problems, and it is a scientific strategy to draw pictures to solve problems.

Knowing the sum and difference of two numbers (generally: large number-decimal number), the application problem of finding the numbers of these two numbers is called the sum-difference application problem, which is called the sum-difference problem for short. The rule to solve the sum-difference problem is that the difference between a decimal and two numbers is a large number, and the difference between the sum of two numbers and two numbers is twice as large.

The difference between a large number and two numbers is a decimal, and the difference between two numbers and two numbers is twice the decimal. So the sum of two numbers plus the difference of two numbers ((sum of two numbers+difference of two numbers) ÷2), and then divided by 2, you can find a large number; Subtract the difference between two numbers from the sum of two numbers, and then divide by 2 ((the difference between two numbers and-two numbers) ÷2) to find the decimal.

How to study mathematics

1. Cultivate interest: Being interested in mathematics is the driving force for learning mathematics. It is suggested to watch some interesting math videos or read some interesting math stories to stimulate interest.

2. Understand the basic concepts of mathematics: Before learning mathematics, we must first understand the basic concepts and terms of mathematics. For example, you need to know the concept of numbers, addition, subtraction, multiplication and division, square sum and square root, decimals and fractions. Please make sure that you master these basic concepts and understand their interrelationships.

3. Establish math habits: spend some time practicing math every day, for example, 20-30 minutes every day.

4. Understanding problems: When learning mathematics, it is very important to understand problems. Ask yourself what problems you need to solve, and master the methods and skills to solve them through thinking.

5. Use tools: You can use some tools to help you learn math, such as online math tutorials, math applications or math homework guidance.