This morning, I was doing my math summer homework. I wrote and wrote. Unfortunately, I met a very difficult problem. I've thought about it for a long time, but I can't figure it out. The problem is this: the circumference of a rectangle is 280 cm and the width is 40 cm. Take one side of this rectangle as the bottom, make a triangle with a height of 50 cm, and find the area of this triangle. I read it and thought: Yes! This question is still a bit difficult! But no matter how hard it is, you have to survive! At this time, I asked my father for help. Father patiently told me how to solve it. Before my father finished, I suddenly realized that the problem was so simple, and the formula was: 280 ÷ 2 =140 (cm); 140-40 = 100 (cm); 100×50÷2=2500 (square centimeter).

I was ecstatic to see that I finally got the wrong question again and again. In fact, any topic is not that difficult, just don't think about it. As long as you think, any topic is very simple.

School is about to start, and my homework is basically finished, so it's not too much trouble. My winter vacation plan has been completed very well. Let's have a new semester, fly high!

2. The second volume of math diary's fifth grade 300 words.

The story says: A mother pig took three little pigs to buy flowers. 20 yuan, a flower, mother pig wants to buy 60 flowers. So, mother pig asked three little pigs, "We want to buy 60 flowers, one in 20 yuan. How much will that cost? " The biggest pig said, "20 times 60 equals 1200 yuan, so it costs 1200 yuan!" " The second little pig said, "No! Don't! It's two tens times six tens equals twelve tens, which is 1200 yuan! The youngest baby pig went on to say, "I think you are all right, but in different ways, they are all the same." "That's right!" Mother pig praised. When it's time to tie flowers, the youngest baby pig first asks, "Now it's time to help flowers. 12 flowers tied together. How many bundles can you tie? "Mother pig didn't make any noise, so everyone just shook their heads and saidno. After a while, the biggest baby pig cried." 1200 divided by 12 equals 100, so you can tie 100 flowers. "

"Although we are tied up, we still have to send flowers to 20 grandfathers. How many bundles will each grandfather divide? " The little pigs said. After 30 minutes, the little pigs said, "Oh! We know that 100 is divided by 20=5, so each grandfather is divided into 5 bundles! "

3. The second volume of math diary's fifth grade 300 words.

In life, mathematics is everywhere. For example: buy food! Buy stationery! Measuring cloth, etc. , all need to use mathematics. This semester, the teacher taught a new knowledge, that is, the multiplication and division of decimals. This knowledge helps me a lot!

Last night, my mother and I went to buy oranges. A kilo of oranges 1.8 yuan. My mother bought 4.5 kg, which should be 8. 1 yuan. But the clerk was careless and didn't know how to calculate it, so it became 9 yuan money. Fortunately, this semester, I used the knowledge of Protestantism, and after doing a calculation in my mind, I immediately corrected the salesman's mistake.

Not only did my aunt, the shop assistant, praise me for my cleverness and my ability to multiply and divide decimals in such a small city, but my mother also praised me for saving her 0.9 yuan on the way home, and the knowledge I learned can be applied in my life.

Yes! If you don't learn this math well, it's not only 0.9 yuan that will lose, but also hundreds, thousands or even hundreds of millions!

4. The second volume of math diary's fifth grade 300 words.

Winter is coming, and the little squirrel has to prepare food for the winter. One day, the little squirrel came to the forest with a big bag on his back and said to Grandpa Pine, Would you please give me your pine cone? Grandpa Pine was generous and said: Pick as many as you want. The little squirrel is very happy. He picked it up and sang. Soon the bag will be full. Grandpa Pine asked: How many did you pick? The little squirrel said, Oh, I forgot! Grandpa Pine smiled and said, "I planted 16 pinecones, and there are nine more. If you can figure out how much you picked, I'll let you carry it. " The little pine tree is in a hurry and can't be counted. What shall we do? If Grandpa Pine won't let him take it away, what will he eat in winter? I will help it.

In math class, the teacher said: knowing the total number and finding the partial number is to remove the known partial number from the total number and get another partial number, which is calculated by subtraction. I soon figured it out that the little squirrel picked 16-9 = 7 (pieces).

Comments: You can apply mathematics knowledge to your life, which shows that you are very serious in listening to classes. Keep trying!

5. The second volume of math diary's fifth grade 300 words.

Today is Friday, and the test paper has been handed out. When I saw the results, I couldn't believe my eyes. I was only 86 points worse than last time. I'm really ashamed and envious to see someone else get a score of 100. I wish I could get a score of 100. But I blame myself for being careless, and I also blame myself for suddenly having a stomachache before I finished checking the first half of the test paper. I really don't know what happened.

And I clearly found a problem wrong, but I didn't have time to correct it. The question is 4 points. If I add up the scores of this question, I can get 90 points. This exam taught me a lesson: don't eat anything except dinner before the exam.

And the check is to write quickly and carefully, don't write typos, or the right one will become wrong, and count it several times. Write the answer quickly and not carelessly, because there is still time to check later.

I will work harder this month, because I will face a final exam instead of a quiz. I will definitely work hard and try my best to get better results in the exam.

6. The second volume of math diary's fifth grade 300 words.

"Wonderful, wonderful, wonderful!" Math is really interesting. Not long ago, we learned a series of knowledge about fractions. How much is 3 divided by 4? I don't know, it's three quarters! That is, divide "1" into four parts on average, and take three of them, that is, fraction and division. Tell you, there are three kinds of scores, true score, false score and identical score. Fractions with numerator less than denominator are called true fractions, and fractions with numerator greater than or equal to false fractions are called with fractions.

Tell you a secret. Turning fractions into decimals can turn fractions into decimals and then into decimals. Divide it into decimal fractions, for example, 4/5,65438+8/00 equals 0.8. How's it going? Relax.

Can 65438+5823 in 07469 be divided into the simplest fractions? I can. The numerator and denominator have three digits and nine digits, and cannot be reduced by two or five. Then add up the digits of numerator denominator, 5+8+2+3= 18, 1+7+4+6+9=27. 18 and 27 are multiples of 3, divisible by 3, and equal to 194 1 in 5823. But now I don't know who to divide it by, but divide it by 3, and the denominator is exactly 5823, which means that the original denominator is three times that of the original numerator. 17469 divided by 5823 equals 3, 5823 divided by 5823 equals 1, 17469 5823 equals 1.

"Interesting, interesting, interesting, mathematics is really interesting!"

7. The second volume of math diary's fifth grade 300 words.

In the evening, my brother said he was hungry and wanted to drink milk powder. Seeing my mother washing clothes, I helped my brother make milk powder. But I didn't know how much water and milk powder I needed, so I ran to ask my mother. Mom told me that I need 180 ml of warm water. I asked my mother how many spoonfuls of milk powder she needed. My mother said, "How many spoonfuls of milk powder do you need for 30 ml of warm water, 1 80 ml of warm water? Calculate it! " When I added it, I counted 30: 30+30 = 60, 60+30=90, 90+30= 120, 120+30= 150,150+30. Finally, the sixth 30 adds up to 180. I quickly told my mother that it was six spoonfuls. Mom smiled and said, "That's right, but if you learn multiplication and division, it will be easier to calculate.". 180÷30=6, which can be calculated soon. " It can be that simple!

Mathematics is around us, I want to study it well!