Writing a thesis in the fourth grade? Is it still alive?
Mathematics on the football field
Last Thursday, Du Zifan and Cai and I played football on the playground. During the intermission, Li Ding and I sat in the corner to have a rest.
At this moment, I suddenly thought of a topic about Xiaohong and Xiaoding playing football, so I asked Li Ding, "Xiaohong and Xiaoding are playing football. Xiaohong kicks 20 balls every hour and Xiaoding kicks 30 balls every hour. It's 1 pm 10. When do Xiaohong and Xiaoding kick 90 balls in the afternoon? "
Li Ding couldn't think of it at once, so he said, "Where are the pens and draft paper?" I think: even if you have a pen and draft paper now, you may not be able to do it! So, I said to Li Ding, "In fact, the solution to this problem is very simple: first, how many minutes does Xiaohong and Xiaoding score a goal on average?" How many minutes does it take to score 90 goals? Finally, add one point ten to the required time, and you can work out when a * * * will score 90 goals. Li Ding asked me with a smile: "Is it because you usually observe life and study mathematics in your life, so you are called' Little Prince of Mathematics'?"
I didn't expect a small math problem to be related to life. It seems that life cannot be separated from mathematics. We always have to deal with mathematics in life, and football field is no exception. For example, the size of a football field has strict numerical regulations: length 90- 120m, width 45-90m and 7 goals. 32m in width, 2.44m in height and 9. 15m in radius. It's really interesting to connect football field with mathematics.
Compare the scores by division.
It is sunny today. I was reading Mathematical Olympiad in Primary School at home, and suddenly I found such a problem: compare11111,1 165538. Suddenly, I became interested and took a pen and "brushed" it on the toilet paper. Soon, I found a solution Is to turn these two false scores into fractions and then use the law of fractions. The smaller the denominator, the greater the score. Solve111111
The world is full of wonders, and there are many interesting things in our mathematics kingdom. For example, in my ninth exercise book, there is a thinking question that reads: "A bus goes from Dongcheng to Xicheng at a speed of 45 kilometers per hour and stops after 2.5 hours. At this time, it is just 18 km away from the center of the east and west cities. How many kilometers is it between East and West? When Wang Xing and Xiaoying solve the above problems, their calculation methods and results are different. Wang Xing's mileage is less than Xiao Ying's, but xu teacher said that both of them were right. Why is this? Have you figured it out? You can also calculate the calculation results of both of them. " In fact, we can quickly work out a method for this problem, which is: 45× 2.5 = 1 12.5 (km),112.5+18 =130.5 (. In fact, we have neglected a very important condition here, that is, the word "Li" mentioned in the condition is "just 18 km from the center of the east and west cities", and it does not say whether it has not yet reached the midpoint or exceeded the midpoint. If the distance from the midpoint is less than 18km, the formula is the previous one; If it is greater than 18km, the formula should be 45× 2.5 = 1 12.5 (km), 1 12.5-65448. Therefore, the correct answer should be: 45 × 2.5 = 1 12.5 (km),12.5+18 =130.5 (km),/kloc-. Two answers, that is to say, Wang Xing's answer and Xiaoying's answer are comprehensive.
In daily study, there are often many math problems with multiple solutions, which are easily overlooked in practice or examination. This requires us to carefully examine the problem, awaken our own life experience, scrutinize it carefully, and fully and correctly understand the meaning of the problem. Otherwise, it is easy to ignore other answers and make a mistake of generalizing.
Write it yourself. It should be simple.
Mathematics thesis, grade four, 200 words. Math thesis, in the fourth grade, I was anxious to divide apples skillfully.
There is a study topic "age" in the fourth grade Olympic Mathematics class. After class, the teacher gave us a thinking question. I've been thinking hard for a long time, but I haven't come up with an answer. I have carefully studied the problem-solving ideas about "age problem" and "inverse problem" and finally got the answer.
The topic is this: The three brothers took apples from their grandmothers respectively. The number of apples received by everyone is their age three years ago. The third child is a clever boy. He suggested that his two brothers exchange apples. He said, "I just need to keep half the apples and give you the other half." Then let the second brother keep half, and let me and my eldest brother share the other half; Finally, I want my eldest brother to keep half, and my second brother and I will share the other half equally. "The two brothers don't doubt what's wrong with this proposal, and they all agreed to the third request. As a result, everyone's number of apples became equal, and everyone got 8 apples. Q: How old are the three brothers?
My idea of solving the problem is this. I infer from the final result, that is, the final exchange result is that each person gets 8 apples, so the eldest brother has 16 apples before separating his own apples, while the second brother and the third brother each have 4 apples. Second brother has 8 apples, eldest brother 14 apples, and third brother has 2 apples. It can be seen that before the apples were separated, the third brother had four apples, the second brother had seven apples, and the eldest brother had 13 apples. Finally, we must pay attention to the sentence "the number of apples received by each person is the age of three years ago" in the title, and add 3 respectively, so now the third brother is 7 years old, the second brother 10, and the eldest brother 16 years old.
Anyway, there are many interesting things in mathematics!
During the "Eleventh" period at the beginning of the fourth grade math thesis, many shopping malls were offering discounts. Taking this good opportunity, my parents and I went to the "Lin Wan" shopping center.
On the second floor, we took a fancy to a suit, and its price tag was 520 yuan. The salesman said, "It's just eleven now. Over 200, you can choose to get a 20% discount or return to 160. Both are similar. "
Is it really similar? I have such a problem in my mind. If you choose a 20% discount, you need 520× 0.8 = 4 16 yuan. And if it exceeds 200, it will return to 160? We have to pay 520 yuan first, and then we will get a coupon of 160× 2 = 320 (yuan), so we actually spent 520-320=200 (yuan). Compared with 200,416, the second one is of course better.
But after getting the coupon? If you buy something from 320 yuan again, you can return it to 160 yuan, and the rebate of this 160 yuan is only 200- 160 = 40 yuan. If you fill in this 40 yuan shopping form, you can return it to 160 yuan. Don't you have a crush? But if you really do this, you will fall into a bottomless pit and spend 200 times 160, 200 times 160 ... you will never spend the rest of the money.
Merchants really try their best to make money!
The fourth grade math thesis (including math diary) 1 day, and my mother bought Dongdong with 5. I saw a Nike one and asked for 540 yuan, but my mother didn't have that much money at that time, so she had to go home and get it. I bought it when I brought it for 5 yuan.
Is it okay to ask for an article in the fourth grade math thesis? I wrote this myself. ...
Clever discount
Today, my mother and I came to the big shopping mall and bought me some clothes.
When I arrived at the mall, I found a big poster posted there, which said, "Great discount on clothes and shoes! Don't miss this opportunity! " As soon as I entered the shopping mall, I found that the things inside were dazzling and lively. We walked to the place where clothes and shoes were sold, where it was more crowded. "Miss, how much is this dress?" "Miss, how much discount are these shoes?" "Waiter, what brand is this dress?" The waiters are all as busy as a bee. My mother and I saw a coat, beige, with a hat at the back and two snow-white balls hanging from the brim. Mother said, "this dress is very good, and there is a hat at the back." It must be easy in winter, and there is a discount. Beautiful and affordable. What do you think? " "I'll take this." I said to my mother. This is, a waitress sister came over and asked us with a smile: "What can I do for you?" "How much discount is this dress?" Mom asked, "This dress 186 yuan is 20% off." The waitress sister said with a smile. I asked my mother, "What is a 20% discount? How to calculate this? " Mom smiled and said, "20% off is 20% off the original price, that is, the original price multiplied by 0.8." "Oh ~" I nodded thoughtfully. Mom asked again, "How about a 30% discount?" "It is equal to the original price multiplied by 0.7." "How about a 15% discount?" "The original price multiplied by 0.85." My mother asked me, and I answered. "All right!" Mom said with a smile. Finally, my mother and I bought a beige coat, and the original price 186 yuan was 20% off. Pink sweater, 15% off the original price in 96 yuan; Beige snow boots, 30% off the original price 1 12 yuan. My mother asked me, "Can you work out how much a * * *?" "Good," I borrowed a pen and paper from the waitress's sister and began to count. "186×0.8= 148.8 (yuan) 96×0.85=8 1.6 (yuan)10× 0.7 = 77 (yuan)/kloc. I said. " Yes! "Mom said to me with a smile. Mom paid the money and we went home.
I have gained a lot today!