1. Understand the concept of multiplication and division: multiplication and division refers to multiplying a number by each number in brackets and then adding the results. For example, we can multiply 9 by each number in brackets and add up the results: 9×(2+3+5)=9×2+9×3+9×5. The result is: 9× 2+9× 3+9× 5 = 45+27+45 =117.
2. Learn the formula of the multiplication table: the formula of the multiplication table is: a× (b+c) = a× b+a× c.
This formula can be used to simplify the calculation, for example: 25× (40+4) = 25× 40+25× 4 =1000+100 =100.
3, do exercises: in order to master the multiplication and division method, you need to do a lot of exercises. Through a lot of practice, you can gradually master the application skills of multiplication and distribution laws. For example, students can calculate the following questions: 23×( 10+5)=? . Then, let the students use the formula of multiplicative distribution law to verify: 23× (10+5) = 23×10+23× 5 = 230+115 = 345.
If the calculation results are the same, it shows that students have mastered the multiplication and division method and the distribution method.
The purpose of the law of multiplication and distribution:
1, simplifying calculation: multiplication and division can multiply a number by each number in brackets, and then add the results, thus simplifying calculation. For example, to calculate 25×(40+4), the problem can be transformed into 25×40+25×4 by using the multiplication and distribution law, so that the result can be obtained quickly. This is also very useful in real life, for example, when calculating bills when shopping, you can quickly calculate the total price of multiple items by using the law of multiplication and distribution.
2. Solve mathematical problems quickly: Multiplication and distribution law can be used to solve some mathematical problems quickly. For example, in some mathematical competitions, there are often some problems that need to be applied by multiplication and division and distribution. These problems usually involve some complicated mathematical operations and skills, but the solution of the problem can be found quickly by multiplication and division.
3. Application to real life: Multiplication and division are not only widely used in mathematics learning and competitions, but also in real life. For example, in the financial field, the multiplication distribution law can be used to calculate the return on investment; In the business field, you can use the law of multiplication and distribution to calculate the total sales of goods; In the field of science, we can use multiplication and division methods and distribution methods to calculate some physical quantities, such as force and work.