Keywords: double digits, grade one in primary school

This article applies to: the first grade of primary school.

Composition source:

This composition is about the first grade of primary school. The topic is: Learning Summary of Unit 3 in Mathematics-Three Numbers Multiplied by Two Numbers. Everyone is welcome to contribute enthusiastically.

Mathematics Unit 3 Learning Summary —— Three Numbers Multiplied by Two Numbers

First, the key concepts to grasp

1, if one factor remains the same, another factor will expand or shrink several times, and the product will also expand or shrink several times.

For example: 6× 2 =126× 20 =1206× 200 =1200.

20×4=80 10×4=40 5×4=20

2. One factor is multiplied or divided by several, and the other factor is divided or multiplied by the same number, and the product remains unchanged.

For example: 18×24=432

( 18÷2)×(24×2)=432

( 18×2)×(24÷2)=432

3. Distance = speed × time speed = distance/time = distance/speed.

Second, the wrong summary.

1, Lili typed 1 18 words in one minute and about (3,540) words in half an hour. Correct answer (3600)

Cause of error: I didn't look at the problem carefully and calculate it into an accurate number.

Wang Shijie processes 72 parts every day. How many parts did he process in September?

10 month =3 1 day 72 × 3 1 ≈2 100 pieces.

70 30

Correct answer: September =30 days 72 ×30≈2 100.

70

Error reason: take September as 10 month and calculate it as 3 1 day. I didn't look at the topic, so I picked up a pen and did it according to the impression of the topic I had done before.

3, a barrel of drinks 4 yuan, buy 3 get free 1, buy 3 bottles at a time, how much cheaper is each bottle?

3×4= 12 (yuan)

12 ÷ (3+1) =12 ÷ 4 = 3 yuan

3×3=9 (yuan)

Correct answer: 3×4= 12 (yuan)

12 ÷ (3+1) =12 ÷ 4 = 3 yuan

3÷3= 1 (yuan)

Cause of error: I didn't understand the meaning of the question, so I calculated the total price of 3 bottles.

4. The product of two factors is 540, where one factor is multiplied by 6 and the other factor is divided by 2, and their product becomes the correct answer (1 120).

Cause of error: calculation is not serious.

Third, the next study plan

1, listen carefully, and you must understand what you don't understand that day, but you can't understand it.

2. When doing homework, look at the questions carefully and find the conditions before doing them.

3, carefully copy the number, not sloppy.

4. Finish your homework and check it carefully; Throw away the answer and recalculate.

Mom's words: from the study of this unit, it reflects many problems. One is writing; Second, the usual knowledge is not solid; Third, the learning method is somewhat rigid. Through your own summary, I hope you can find the gap and do it according to your own study plan on the wrong problem set to avoid the above mistakes in future study. Mom believes you!

Young man!