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"Fill in the same number in parentheses" is a type of question that first- and second-grade primary school students should master, but when students do this kind of problem, there are often two situations: First, they do not understand the requirements for doing the problem. compare

author:Reminiscences of dreams

"Fill in the same number in parentheses" is a type of question for first- and second-grade primary school students to master, but when students do this kind of problem, there are often two situations:

First, there is no need to understand the requirements for doing the question.

For example: 11-(3)=(15)-7

Looking at the number filled in the parentheses, the equation was established, but the numbers filled in the parentheses were not the same, and the teacher unceremoniously typed the wrong number when correcting. This situation is caused by the students' lack of seriousness and carelessness in reading the questions, like the above questions should be 11-(9)=(9)-7

It can be seen that the requirements for students to read before the questions are very critical, and they must develop a good habit of reading the questions carefully.

The second is that there is no way to master the problem.

When many elementary school students do the "fill in the same number in parentheses", because they have not mastered the method of answering the question, they repeatedly try to take the numbers until it is appropriate. For example, 16-( ) = ( ) + 2, some students start from 1 and try until 7 to get 16-(7) = (7) + 2. Is this method possible? It's okay, but it's too time-consuming. Today, the teacher told everyone that the method of doing this kind of problem, as long as you master the method, you can do it correctly and quickly.

1. The two sides of the equal sign are minus signs

Example: 10-()=()-4

Add the first and last two numbers 10 and 4 and divide them into two parts, 10 + 4 = 14, 14÷2 = 7, so the number in parentheses is 7. 10-(7)=(7)-4

First-graders have not learned to divide, so they use the method of dividing the numbers they have learned, dividing 14 into two identical numbers, and 14 can be divided into 7 and 7. The recipe is: the two sides of the equal sign are minus signs, and the beginning and tail are added and then divided equally.

2. The two sides of the equal sign are addition and subtraction

Example: 15-( ) = ( ) + 7

When encountering both sides of the equal sign, one side is a plus sign, the other side is a minus sign, and it is not possible to use the above method. So what to do? Remember this method: subtract the decimal number from the large number and divide it into equal parts. 15-7=8,8÷2=4, 4 in parentheses, 15-(4)=(4)+7.

First-grade children still use the method of number division to divide, dividing 8 into two identical numbers, 8 can be divided into 4 and 4.

Finally, I would like to emphasize again that when doing the "fill in the same number in parentheses", memorize the mantra: the two sides of the equal sign are minus signs, and the beginning and tail are added and divided equally; the two sides of the equal sign are added and subtracted, and the beginning and tail are subtracted and then divided equally.

"Fill in the same number in parentheses" is a type of question that first- and second-grade primary school students should master, but when students do this kind of problem, there are often two situations: First, they do not understand the requirements for doing the problem. compare

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