Math diary, Grade Four 1 This summer vacation, my mother took me to visit Hong Kong Disneyland. Compared with the mainland, Hong Kong has a very small area, with a population of about 6.6 million, with a total area of 1070 square kilometers. The world's smallest Disneyland located on Hong Kong Island has an area of only 126 hectares (3 10 acre). The tour guide said, "If you don't play anything, you just need to walk around/kloc-0. Let me show you my trip to Disney!
First, we went to Mickey's photo studio to take photos with Mickey and Minnie. When we got there, we saw: Wow! There was a long queue in front of the photo studio, almost 25 meters long, and my mother took me with all her strength to squeeze in. Finally, we went to the Cinderella Carousel to play. I got on the Carousel and took a closer look. The Carousel has three circles, and each circle has 15. I calculated:15× 3 = 45 (one). Wow, so many! We turned round and round on it, feeling like the happy scene when riding a horse on the prairie. The following fantasy space trip, adventure world, mini-world, the performance of the lion king, and the Mickey Awards Gala all left a deep impression on me.
Disney's things are very, very expensive. A bottle of coke costs 17 yuan, which is more than ten yuan more than ours. At lunch, a bowl of noodles is for 50 yuan. Have you ever eaten a bowl of noodles from 50 yuan? It's really expensive! Before leaving Disney, everyone wants to buy some souvenirs. My mother bought me an umbrella of Princess Disney, which cost a whole 100 HK dollars. I thought again: we only need 20 yuan for each umbrella here,100 ÷ 20 = 5 (handfuls). Wow! This is too expensive!
When I got on the bus and left Disney, my mother asked me, "How long did we play from 8 am to 6: 30 pm today?" I thought about it: 6: 30 pm is 18: 30, 18: 30-8: 00 =10: 30.
The bus started, and I reluctantly bid farewell to Disney Park: Goodbye, we will come again next time!
Math diary, Grade 4, has been staying at home this winter vacation because of the epidemic. One day, my mother said, "Let's use our brains to play a game. As long as you name two numbers at will, I can immediately calculate their sum and subtract their difference."
I was a little incredulous. I asked, "Any number is ok?" Mom said, "Yes, of course!" " So, I thought about two numbers and said to my mother, "452 and 637, can you immediately tell the sum of 452+637 MINUS the difference of 637-452?" Mom immediately replied, "It's 904." I was still a little skeptical, so I quickly took the pen and calculated it vertically, and the result was the same as what my mother said. I thought to myself, it must be that my figure is too small, and it is difficult for my mother to make two bigger figures. I was a little unconvinced and said, "9734 and 6420, you can't figure it out now, can you?" "12840, it must be correct!" Mom said confidently. I made a vertical calculation again, and the answer was the same! Now, I have nothing to say and have to admire my mother. I said, "Mom, you must have some secret, otherwise it wouldn't be so fast. Please tell me quickly!" " Mother said, "I'll give you three questions. After you finish, look for the rules and see if you can find the secret." So, I started the problem seriously.
①26 and15: (26+15)-(26-15) = 30.
②637 and 200: (637+200)-(637-200) = 400.
③3 186 and1040: (3186+1040)-(3186-1040) = 2080.
After working out the answer, I observed it carefully for a while and said happily to my mother, "I know, the final number is twice as much as the smaller one." My mother asked me to check a few questions myself, and it was true.
Then, my mother asked, "Do you know why the number is twice as large as the smaller number?" I shook my head to show that I didn't know. So, my mother said, "We can use letters to represent any number, and we can also write such a deduction process (A+B)-(A-B) = A+B-A+B = B+B = 2B. You will understand this secret more deeply when you learn more mathematics knowledge in the senior year."
After listening to it, it suddenly dawned on me. It turns out that there are so many mysteries hidden in a small number, and I think mathematics is really interesting.
One day in math diary, Grade Four, a teacher wanted to test his students' mathematics. So, he said in a math class, "I'll give each of you a piece of paper and write any four numbers on it. I dare say that the difference between two numbers written by each person can be divisible by three!" " The students didn't believe it, so the teacher handed out paper. After a while, everyone wrote it.
When the students read the written numbers one by one, the teacher can find two numbers divisible by 3 on business trip. No one is an exception! For example: 1963, 1765, 1736,1376 ... the difference between the two numbers can be divisible by 3. What's going on here? It turns out that if any natural number is divided by 3, there are only three possibilities for the remainder, namely, the remainder 0, 1 and 2. If natural numbers are classified according to the remainder after division by 3, they can only be divided into three categories.
And the teacher asked the students to write four numbers, so there must be two numbers with the same remainder. Subtract two numbers with the same remainder (decrease the number of large numbers), and the difference obtained can of course be divisible by 3! After the students knew it, they cast admiring eyes on the teacher. Students, don't you want to have a try?
Location: Symbol Kingdom
Characters; =、÷、×、+、-、（）
My name is equal to number. Look how neatly I comb my two braids!
?: My name is Division. Although I am not very good-looking, I am very useful!
X: My name is multiplication sign. I look wrong, but don't write me wrong!
+:My name is plus sign, and I look like ten, but I'm not ten, so make me very clear!
-:My name is minus, just like one. How beautiful and neat!
One day, the symbol girls were noisy in the symbol kingdom.
Book: I'll give you a 1 question, and you should take your seats. The topic is this:
3333=6
The symbols are all standing, and they are not wrong!
(): Fortunately, there is no such ugly thing as the slogan, otherwise our neat queue will become ugly ducklings if it is chaotic.
At the words of (), the boat bowed its head.
?: Are my two black balls so annoying?
Book:+How can you say that? We are all good friends and must help each other!
The symbols are ashamed, and they have let Yan join them again. Do you know how they are combined, children?
Math diary, Grade 4, remembers a math class, and the teacher gave us an interesting lesson. Although the class is only 40 minutes long, we feel like we just started the class. Why do you feel this way? Because Mr. Wang's teaching is so interesting, we can't wait to come to math class on Saturday and Sunday.
The teacher came into the classroom with a big smile on her face. "Hello, classmates." We said, "Hello, teacher." Please sit down. The teacher said, "Today, let's review Unit 3: Understanding of Angle and Triangle." Teacher Wang led us to review the measurement of angles, drawing angles, the classification of triangles, and the comparative size of angles ... When the teacher talked about the degree of the sum of the internal angles of triangles, the students said in unison, "The sum of the internal angles of triangles is180". The teacher smiled happily, but at this moment, when Mr. Wang saw someone deserting, he pretended that it was nothing, called the classmate and asked, ". "180" The teacher then drew a big triangle and a small triangle on the blackboard and asked, "Whose inner angle is bigger than theirs?" "Big Triangle" students immediately raised their hands. If they stand on the podium, their hands will look like a small forest! "XXX, you say!" "It should be the same size." "Yes, XXX, did you hear that?" The teacher went to the table in the third row in the south and said, "Turn to page X of the textbook and look at question X." The book drew a big triangle and was divided into two small triangles on average. "The sum of the internal angles of the big triangle is180. What is the sum of the internal angles of one of the small triangles?" The students say "90" and "wrong" together, and they say "I don't know" and "Alas ... the teacher calls me!" The students couldn't sit still. XX said, "Miss Wang is so accurate, why can't she do anything?" "Miss Wang is really amazing." Miss Wang found another classmate, and the classmate said, "90" and we sighed, "360" and "I don't know" ... At this moment, a small forest came out. The teacher laughed again and again, and the students also laughed. The teacher called my deskmate "180" again and answered loudly. "Alas," the students sighed again. First, they didn't call themselves. Second, they finally found a meeting.
Everyone was just about to continue the class when the bell rang, and the students "ah!" This will be more! " "Class is over so soon, isn't it?" Teacher Wang said, "Yes, the bell is ringing. Class is over!" "Stand up" "Hello, teacher! Ha ... No, the teacher has a rest! " Teacher Wang smiled knowingly and left.
We are looking forward to the next interesting math class, which I will never forget!
Fourth grade math diary 5 integer fraction decimal prime number composite negative positive function derivative high mathematical olympiad! I hate to grind my teeth at the thought of it.
Since the first grade, the subject I hate most is mathematics. For example, what is 100 million, you can tell at a glance that there are only a handful, and there are so many zeros; What "π" can't be eliminated, and it's so troublesome to calculate it; What's the common multiple and common factor? How can I make it clear? Ah, Aquinas! Forcing me to ask my classmates for short division; I really can't draw a fan-shaped, bar-shaped, broken-line statistical chart well. Alas, I can't even give a grid to this question. Hey, I feel dizzy at the sight of this algebra and geometry. What nonsense is science? It's so boring and annoying. I'd better learn Chinese.
The above is not the most important thing. The most important thing is that I am always careless, so the questions that I could have done were deducted together with the questions that I couldn't do, which led to my math performance standing out in the class. Infinite cycle of decimal low scores to me, countless bright red forks shattered my weak heart, meowed, I have long been disappointed in my math scores. Mathematics is the most important thing in schools now! My scar!
No, on a recent day, I finished the math problem with a sad face, but I was lazy and didn't check it with a clear conscience. As a result, as soon as the homework was handed out, all the questions I was dumbfounded at once were crossed. Huh? What happened? I looked at the surviving questions and became confused. Suddenly, my eyes went black, and I found myself making a serious mistake, that is carelessness. It's all wrong! I wasn't like this before. My eyes were bloodshot and a hatred came to my mind: "Math, you humiliated me, you discouraged me!"! I hate you! I hate you! " I was so upset that I immediately threw my exercise book back. I vowed never to listen to math class again! Just idle away your time. It's better not to study hard than to make a mistake, so you can save some dignity by dying. What's the use of sweating again? It will be wrong anyway. Isn't this a waste of energy and time?
However, after I swore, I couldn't help running to the table to do math problems, and I couldn't help but maintain a high degree of enthusiasm in math class. Hey! I really hate math, I hate it, but my hate for it can't match my love for it after all!
Math diary, Grade 4, has mathematics everywhere in her life. For example, how many steps are there for us to go upstairs and downstairs? How many light bulbs are there in the house? How long does it take us to have a meal ... Today, I wonder what we can do in three minutes.
After getting up in the morning, I began to wash my face and brush my teeth. My mother got up much earlier than me, and now she is hanging clothes. I felt a little bored, so I picked up my watch and began to time my mother to see if she could dry the clothes in a few minutes. After a while, I pressed the stopwatch, and at first glance, no more, no less, just three minutes. My mother saw me timing, and said to me angrily, "What's the use of timing here?" Just think about how long it will take you to do things! " After listening to my mother, I said, "I only need three seconds to open the door!" " "Think of something useful!" Mother said that and went to cook breakfast. I sat down at my desk, thinking about the time I needed to do things. "I do a list of oral calculations to 1 minute; It takes 1 hour to read a book; It takes 10 minutes to wash the bowl once; Have breakfast ... ""Guo Songyuan, have breakfast! " I just thought of eating breakfast, and my mother really wants me to eat it. I quickly ran to the dining table, picked up my watch and put it aside, ready to time again. After pressing the timer, I wolfed down rice congee in front of me and thought to myself, "How long will it take me to have breakfast?" As I thought about it, I pressed the pause button on my watch and looked at the time-15 minutes and 23 seconds! "It turns out that I need'15 minutes and 23 seconds' for breakfast!" I muttered to myself. Seeing that I was so bored, my mother gave me a task: count the number of small squares on the kitchen sliding door within 5 minutes.
I said, "This is not easy! The little man * * * has six rows, each row has 18 small grids, and the formula is' 6x18 =108 (pieces)'. There are two doors, and there are small grids on both sides of each door. The formula is:'/ Mom saw that I got it right and gave me a favorable look.
There is mathematics everywhere in life. As long as you have a pair of eyes that are good at discovering, you can discover the mystery.
Math diary, Grade 4, 7 Slowly, mathematics has become an unfamiliar word in people's minds. Today, my father gave me a math problem. Let's have a look!
Topic: A rectangular aluminum sheet with a length of one meter 20 cm and a width of 90 cm can be cut into a disc with a diameter of 30 cm. How many pieces can it be cut into at most?
I think: should we first convert the unit to 120 cm, then multiply it by 90 cm and divide it by 30 cm? Or convert the unit, divide it by 30 cm to find the multiple, and then multiply it? When these two methods were in a mess in my mind, my mother came to the rescue. I told my mother my two methods respectively. My mother thought for a moment and said, "This topic should be done in your second method. First of all, if you do it by one of your methods, it is 120x, etc. 10800 (square centimeter) 10800÷30=360 (blocks). How can there be so many here? If the second method is used, it should be120 ÷ 30 = 490 ÷ 30 = 33x4 =12 (block), which is more reliable. Secondly, you can use drawing to find it. " Mom said, gave me a look, and I immediately took a heart, ran to get a piece of paper, pen and ruler and began to draw. Soon finished, a rectangle, with 12 squares, each square has a circle, one *** 12. In the end, it proved that my first method was wrong and the second method was correct! My mother suddenly asked me, "Will it be now?" I said loudly, "Yes! ..... "After hearing my fluent way of doing this problem, my mother said," But remember, it's not lip service! " "Be sure to abide by it!" I made a policeman salute, and my mother couldn't help laughing.
After passing this math problem, I found that my math is not very good. I must work hard! Be a powerful math doctor! Come on!
Math diary 8, Grade 4 Whenever I see those papers at home that got full marks, I can't help but think of the story told by my mother-the revelation of decimal point.
That night, after my math homework last night, I finally had a rest, but I heard my mother shout, "Wei Liu, why did you do something wrong again?" I walked over impatiently, looked at the question, and said disapprovingly, "Didn't you just miss a decimal point? What's the fuss?" Mom immediately put a straight face: "What? So that's how you look at the decimal point, so I'll tell a story about the decimal point. "
19xx On August 23rd, the former Soviet Union Soyuz-1 spacecraft sent an urgent message that the deceleration parachute could not be opened, and the former Soviet government decided to announce the news of the spacecraft's martyrdom to the people of the whole country! After hearing the news, people all over the country sighed and felt sorry for Vladimir Komalov, a heroic astronaut. When the Soviet government connected it with the video installation system of the spaceship, Vladimir Komarov appeared on TV. He said to his old mother, "Mother, I see you clearly, including every hair. What about you?" "Me too!" The old man said with tears in his eyes. "Daughter, how are you? You can't cry, you must be strong and live. You must be careful in life. The accident is due to the ground inspection, ignoring a decimal point ... "
There were only 7 minutes left before the crash, and he said goodbye with a smile ... After listening to my mother's story, I realized something. On the next day's math exam, I carefully checked every question and every decimal point. Finally, I got 100. I think: If I hadn't been inspired by my mother's story, I wouldn't have got 100 at all.
Now, I finally understand the real inspiration of the story my mother told me: you can't be careless about life, or even a trivial matter will cost you a heavy price, even if it is never made up. The revelation of decimal point has benefited me for life.
Math diary, Grade Four, Composition by math diary, Grade Nine11Monday, October 6th, sunny.
This morning, I went shopping with my mother in the supermarket. There are many things in the supermarket, including food, drink, use and many toys. We first came to the food section and bought a box of my favorite good friends pie 15.7 yuan. My mother gave me 100 yuan to settle the bill. 100- 15.7=84.3 yuan.
We came to the vegetable area again, and my mother bought 2.2 yuan, a green pepper. Chestnut 12.4 yuan, bean sprout 4.8 yuan and potato 4.4 yuan, we spent * * * in the vegetable area (2.2+ 12.4+4.8+4.4=23.8 yuan), 84.3 yuan MINUS 23.8 yuan, and now there is still 60.5 yuan left. I want to eat milk yellow buns. We came to the cooked food area and bought a bag of milk yellow buns to go to 5.9 yuan. After deducting 5.9 yuan from 60.5 yuan, there was still 54.6 yuan left. My mother asked me how much the line cost. Let me see (15.7+23.8+5.9=45.4 yuan). How much is left? Mom gave 100 yuan, and we spent 45.4 yuan (100-45.4=54.6), leaving 54, 6 yuan.
I'm so happy to go shopping in the supermarket today!
Math diary Composition in Grade 4 On the weekend of 2, my mother sat in front of the computer and surfed Taobao. I asked my mother what to buy. Mother said, "The Spring Festival is coming soon. I want to buy a pair of shoes for you and your sister." I asked, "Mom, why don't you go to the store to buy it?" Mom said; "The price of the shoes I like is 20% off for each pair of 200 yuan, which is 160 yuan. How much do you calculate for two pairs?"
I quickly calculated: 160*2=320 (yuan)
Mom said, "That's a good calculation. Then you can calculate the online discount of 60%. How much does it cost for two pairs?"
I went on to say: 120*2=240 (yuan)
Mom asked again, "How much is it cheaper to buy online than in the store?"
I said loudly: 320-240=80 (yuan)
Mom said, "Do you calculate quickly? Now you know why we don't go to the store to buy it?"
I said, "I see, when can we get our new shoes?"
Mom said, "The courier will deliver it to your home at noon tomorrow, so just wait for the goods to be received."
Math diary 10 mathematics in grade four is closely related to our daily life, especially in commodity trading, mathematics is brought into full play; Carelessness can lead people astray.
On the occasion of the Spring Festival, my mother and I went to the "Heart of the City" shopping mall. Suddenly, my mother saw the sign that the shops selling cotton-padded clothes were discounted when they were limited. My mother was trying to buy a cotton-padded jacket for my father. At that time, my mother took a fancy to one and asked the waiter how much it cost. The waiter said that this dress was new this year, and the original price was 680 yuan. Now she is doing activities at a 25% discount, or attending a full 150 gift.
I began to calculate in my mind that 680 times 5 10. If I attend another activity, I can get a 200 yuan gift certificate by paying 680, and I can buy a pair of pants by adding 180 yuan. The money for buying a pair of pants is 380 yuan, and I can return a gift certificate of 100 yuan. If I add 99 yuan, I can buy an induction cooker, and finally I can get a 50 yuan gift certificate. If you add 75 yuan to buy an electric kettle, this means that if you spend 25 yuan to buy two pairs of socks next to you, and make up enough money for 150 yuan, you can get a gift certificate from 50 yuan ... Before I knew what this account was about, my mother only took that dress to pay the bill. I wanted to ask my mother what kind of activities she participated in, but I didn't have a reliable basis.
When I got home, my mother asked my father to try on cotton-padded clothes. I introduced the activities of the shopping mall to my father, and my father said; "Mom, it's a monkey spirit." I asked my father why. Dad said: "The purchase price of clothes in the mall is about 40% to 45% off the sales price. After 25% off, he still makes a profit. In order to attract customers to spend more, if you really need something, it is favorable for customers. When you buy something blindly for which gift certificates, which endless gift certificates attract you to fall into the trap of merchants." Oh; I seem to understand the intention of the merchant. No wonder some people say that "sellers are always better than buyers".
It's really a science to learn mathematics well and make proper use of it. Different positions have different planning and development skills and methods. I want to study mathematics well and apply it in my life.
Math diary 1 1 We were studying litres and milliliters at school. The teacher asked us, "Can you guess how many milliliters of water a dripping faucet can drip in one minute?" Some say "20 ml", others say "30 ml". The teacher said, "Go home and find the answer by yourself!" " .
I am a curious child. As soon as I got home, I took my mother to do an experiment. Start clocking 1, 2, ... 60, time is up! I picked up the measuring cup and measured the water. 10 ml of water, only 10 ml of water, so little. My mother seemed to see through my heart and said to me, "Think about the four faucets in my house. If each faucet is not closed tightly, how much water can be wasted in one day and how much water can be wasted in one year?" . I calculated it carefully: 10×60×4× 24=57600ml=57. 6L, the water wasted in one day is 57. 6 liters, the water wasted in one year is: 57. 6×365=2 1024L=2 1。 024 tons. And we need to waste more than 80 yuan a year per ton of water calculated by 4 yuan. I think: there are 20 faucets in our school: water wasted in one day is 20×10× 60× 24 = 288000ml = 288L, and water wasted in one year is 288× 365 =105120L =/kloc-0. 12 tons, wasting 420 a year. 48 yuan, though not a lot, still lost a lot. If you donate the wasted water to those water-deficient disaster areas, it will not be a small sum. This is what I think. If1300 million people don't turn off the tap after using it, how much water can they waste? I began to calculate:
Waste of water in one day:10× 60× 24×130000000 =18720000000000 ml =187200000000 l =1872000000.
18720000×4=74880000 yuan; Waste of water in one year: 18720000 ×365=6832800000 tons; 6832800000× 4 = 27331200000 yuan.
The total number of 2733 1200000 is about 30 billion! This diversity is enough to bankrupt us. This water is enough to fill the Yangtze River and the Yellow River, and this water is enough for many families!
I call on everyone to save water and protect water resources, in order not to let the last drop of fresh water be people's tears!