On the day of math diary 1 in the fourth grade, I had nothing to do and wanted to help my aunt buy food. I thought I could finish math diary.
I came to the vegetable market and it was very lively. The noise is very annoying. I immediately bought my favorite chicken leg and couldn't wait to get there. I immediately asked my boss a few dollars each, and the boss replied, "One from 4.5 yuan." I took out 10 yuan and gave it to him. He gave me the money and I left. I ran away without paying attention. When I went shopping, I found that I was 50 cents short, and I was going to change it. I was really confused at that time and immediately went to the place where I bought chicken. I am really careless. Why didn't I notice? The boss is also warm-hearted. He gave me the money without saying anything. I bowed my head in shame, said "thank you" and left.
Later, I bought a lot of things, none of which counted. I decided to count patiently and finally got it. The result is the answer: 45.3 yuan. Dad told me how 50 yuan left only 4 yuan. What should I do? With a loss of 70 cents, what can I say?
As soon as I got home, I came to my father and said, "Dad, I'm sorry, I miscalculated the money." Dad smiled and said, "It doesn't matter. There must be careless mistakes in life. " This time, I forgive that I can't do it any more. I heard what to say. Therefore, you can't make careless mistakes in general mathematics. If you make careless mistakes, you will suffer. You can't go shopping after that. Understand the last lesson.
Math diary is in Grade 2 and Grade 4. I learned a lot about this unit in Friday's math class. Let me tell you something.
First of all, let's recall which units we have learned before. I tell you, we used to learn units with length, such as meters, decimeters and centimeters, and their forward speed is 10. We also learned the units of area, such as square meters, square decimeters and square centimeters, and their advancing speed is 100. But what is the unit of volume and the unit of volume? Now let me tell you one by one. The unit of volume is the same as unit of volume, which is called cubic centimeter, cubic decimeter and cubic meter. But what should we do in order to distinguish units conveniently? Let's do an experiment first. First, fill a container that can hold one liter with one liter of water, and take out a cube with an uncovered volume of one cubic decimeter. Pour a liter of water into the cube. Is this cube full of water?
Through experiments, we proved that one liter of water is equal to one cubic decimeter (volume) and one milliliter is equal to one square centimeter (volume).
Now let's learn the similarities and differences between volume and volume: the similarity is that their units are the same, but the difference is that volume refers to the space occupied by an object, and volume refers to the volume of an object that can be accommodated in a container. And 1 l = 1 cubic decimeter, 1 ml = 1 cubic centimeter. Let me tell you what the forward speed of cubic meters, cubic decimeters and cubic centimeters is. Their advance payment rate is 1000. Why on earth? Because 1 l = 1000 ml, and 1 decimeter cubic = 1000 cubic centimeter. So it is 1000.
Now, will you?
Math diary, fourth grade, March 6th, Wednesday sunny.
My uncle's house is being decorated these days. My uncle asked me to go to the decoration material center with him to buy glue for decoration.
My uncle and I came to the decoration materials center with great interest, and the goods inside were dazzling and countless. The two of us ran to the glue shop and found that there were two kinds of glue in it: one was 3 cans 199 yuan, and the other was 7 cans for 299 yuan. Both glues have the same quality and formula. My uncle asked me, "aren't you good at math?" Then you can figure out what glue is cost-effective? " I thought to myself: what should I do if these two kinds of glue cost a can of money and cannot be removed at all? It suddenly occurred to me that these two kinds of glue can buy the same amount, just compare them! I think: the least common multiple of 3 and 7 is 2 1, so buy 2 1 can for both. 199 yuan three cans, 2 1 can, 199× 7 = 1393 (yuan) and 299 yuan seven cans, 2 1 can, 299× 3 = 897 (yuan) and 299.
Later, my uncle praised me and said, "It seems that your knowledge of mathematics is not bad. I will ask you to answer any math questions in the future! " "Listen to my uncle, my heart is as sweet as honey.
Math diary, Grade 4 Today, I followed my mother to the market to buy food. Mom said, "I will test you today. Will you buy your favorite dishes?" My mother gave me 20 yuan money to watch my performance. "Make sure the task is completed." I said confidently. So, I walked and watched, and came to the vegetable area. At this moment, I saw an aunt selling white and tender fresh mushrooms. I think: the leftovers at home can be cooked with mushrooms. So, I asked the aunt who sells vegetables: "Aunt, how much is a catty of mushrooms?" Aunt smiled and said to me, "Little friend, this mushroom costs 7 yuan a catty. How much catty do you want?" "Aunt, I only need to buy half a catty." I think: 7 divided by 2 equals 3.5 yuan, 20 minus 3.5 equals 16.5 yuan. After thinking about it, I gave my aunt a note of money from 20 yuan, reminding her that she still needs to find me 16.5 yuan. I went to the meat department again and saw an uncle selling meat, so I asked, "Uncle, how much is a catty of meat?" "Then I'll buy a catty." I want to subtract 10, which is equal to 6.5 yuan. I handed the 10 yuan in 6.5 yuan to my uncle.
When I came out of the food market, my mother smiled and said to me, "Learn to buy food!" " When she saw that I had both meat and vegetables and 6.5 yuan in my hand.
Through this test, I feel that there are many mysteries of mathematics hidden in our lives, and the ability to learn mathematics is really important. And don't be proud. You should study hard and master more math skills in order to apply what you have learned and solve the problems around you.
Hua, a fourth-grade mathematician in math diary, said: "The universe is big, the particles are tiny, the speed of rockets, the cleverness of chemical engineering, the change of the earth, the mystery of biology, and the complexity of the sun and the moon are everywhere." Especially in the 2 1 century, the application of mathematics is everywhere.
It's rare to have a holiday today, so I took my parents shopping when the interest class had a holiday. Actually, it's more about helping me buy books than shopping!
My parents also read my mind and said, "it is ok to buy books, but you have to work out the discount price of books." How about it? " I readily agreed.
The first book I want to buy is Aesop's Fables. The price of this book is 10 yuan, but because it is a holiday, I should get a 10% discount, so I should multiply it by 0. 9, but I haven't learned to multiply numbers with decimal points, so I want to use simple calculations. "Oh, yes, you can put 0. 9 as 1, then 10x 1 = 10 is 10 ÷10 =1,and then use1. Dad smiled and said, "What about 20 yuan for a book? "Yes, if it is not an integer, wouldn't it be hard to forget? So, I thought hard again. : "hey, I know! "You can put 0. 9 expand 10 times, that is, 9, and then use 9X20 = 180. Because we expanded 10 times in the calculation, we need to reduce 10 times now, that is, 180 ÷ 10 = 18 (yuan
So I told my dad with confidence. This time, my dad showed a approving smile! I also got the book I wanted.
This made me really understand Hua's famous saying. I think: with the growth of grade, you must know how to make full use of what you have learned in class in your life in order to further improve your grades!
Math diary, Grade 4 6 Today, Teacher Zheng doesn't know what medicine is sold in the gourd? Actually gave us a 79.00438+0 < () < 79.438+0, which means how many decimal places can be filled in brackets? Some said ten, some said nine, and some said that the bell rang at this moment, so the teacher had to say: this question is a bit difficult, let's go back and think about it.
I thought to myself: Is this a difficult question? But what is the answer? There is only one answer? Question marks keep popping up in my mind. How many decimals can be filled between one decimal and another? what do you think?
I looked out the window, hoping to find some inspiration. Suddenly I saw a tricycle go straight, but turned a corner at the crossroads. My eyes lit up! Thought: Why do I always think in one direction? You can also turn a corner like riding a tricycle! Take 79. 1 > () > 79.05438+0. Each number has only one phase.
When the difference is 0.0 1, it is 8. What's the difference between 0.00 1 and 0.000 1? There are countless correct answers. I was ecstatic and jumped three feet for joy.
When doing math problems, we often can't think from one angle. If you want to beat around the bush, you can think from another angle or multiple angles, which can better solve math problems.
Comments: Hong Xiang, a student, can learn from the common life phenomenon of tricycle turning: we can't just think from one angle, but we can think from another angle or multiple angles to solve math problems better. This feeling is commendable.
One night in math diary's fourth grade, my mother and I went to Dennis's supermarket to buy food.
As soon as I entered the gate, a smell of Guandong cooking came to my nose. Ah, I suddenly want to eat! My mother bought me three strings, one of which cost 9 yuan.
Go in, it's the milk and beverage section. The promotion aunts of Yili and Mengniu are recommending their dairy products to customers. I like Yili's yogurt best, but there is no yogurt at home, so my mother bought it and spent 68 yuan. My aunt also gave me a set of watercolor pens as a gift. Hee hee, I can use it when I go home to draw!
Continue to go inside, cross the biscuit and snack area, and we come to the fresh vegetable area. See the price tag: radish 1 yuan/kg, potato 0.9 yuan/kg, cucumber 2.2 yuan/kg. We're going to make fried noodles with cucumber and shredded radish for dinner today, so we bought two cucumbers and a big radish, which make 5.4 yuan.
My mother asked me what else I needed to buy. I looked at the goods on the shelves around me and answered her, "buy another can of eight-treasure porridge." Eight-treasure porridge original price 4.2 yuan/listen, member special price 2.9 yuan/listen. I took a bottle of longan and lotus seed flavor.
Time to check out. While waiting in line, my mother suggested that I work out how much money * * * needs to pay. I began to use the same method to calculate in my mind: 9+68+5.4+2.9=85.3 yuan. Soon, after scanning the bar code, the cashier aunt said, "It's ***85.3 yuan", haha, the score is exactly the same!
On the way home, I thought to myself: fortunately, it was just an addition problem. If it's a mixture of addition, subtraction, multiplication and division, I'm afraid I can't calculate it by mouth!
Math diary fourth grade summer vacation, my mother and I went to the mall to buy clothes. However, I think the price there is very strange: saying "buy 100, get 100" means we don't need money?
Mother said, "Silly daughter, how can you not use money?" I said, "Because it says buy 100, get 100, which means 100- 100=0, so no money is needed!" Mom said, "that's how you calculate." If so, everything in the mall is free, and many guests will come. This mall will lose a lot. " Mom also said that you only need 50 yuan to buy 100 and get 100, you know?
After listening to my mother's analysis, I still don't understand. Why? It seems that I still have to go to the shopping mall to make a serious investigation or consult Ceng Laoshi to see what she has, because I know there is still a lot of math knowledge I haven't understood yet.
With a happy mood, I came to the school to ask Ceng Laoshi a math question. Ceng Laoshi said, "In fact, some of them exceeded 65,438+000. For example,109,200, 189 or above ... "
The teacher added, "If the amount exceeds 100 yuan, you will get a coupon of 100 yuan. Customers still have to spend enough money 100 yuan to get the coupons. Not as free as you said. " Ceng Laoshi praised my questions and welcomed me to ask more questions in the future.
Math diary, Grade 4, Grade 9, I just finished my homework this evening. At this time, the doorbell rang, and I was very happy, because I knew that this was my mother's return. My mother had not talked to me for a long time.
After the doorbell rang for five seconds, I quickly ran out of my desk to open the door. As soon as my mother entered the room, she said to me, "Hey, I brought back 1 box of Japanese chocolate!" I immediately cheered: "Yes, it's very kind of mom. Come, give it to me! " "Mom said," mom is not good. I can't just give you chocolate. You must answer my question. "After hearing this, I thought to myself: I am not afraid if you want to test me again!
Mom has a problem: I think it's a matter of reasoning this time. Xiaoming said to Xiaodong yesterday: "Yesterday, there were 10 students in our family. My mother took out a bag of sweets, which contained 54 sweets, and distributed them to small guests, but the number of each person was different. The most frequent one is 10. " Hearing this, Xiaodong immediately said, "You are lying! You lie! " I asked you why Xiaodong said Xiaoming lied. At this moment, I had a brainwave and thought that I had learned "simple reasoning" before. This question is different. I began to calculate: the most one got 10, so there can't be duplicate numbers. Let's assume that the first one gets 65,438+0 candy, the second one gets 2 candy ... and the tenth one gets 10 candy. Xiao Ming is lying, because he said that the bag of candy has 54 pieces, but actually one person wants 55 pieces, so Xiao Ming is lying.
I told my mother what I thought just now. My mother said I was smart, so she gave me this favorite Japanese chocolate. I think mathematics is really everywhere. Even I have to use math to get these chocolates. I got it, which is the crystallization of my efforts, hee hee!
Math diary, Grade 4 10 Today, I went to the market to buy food with my mother. Mom said, "I will test you today. Will you buy your favorite dishes?" My mother gave me 20 yuan money to watch my performance. "Make sure the task is completed." I said confidently. So, I walked and watched, and came to the vegetable area. At this moment, I saw an aunt selling white and tender fresh mushrooms. I think: the leftovers at home can be cooked with mushrooms. So, I asked the aunt who sells vegetables: "Aunt, how much is a catty of mushrooms?" Aunt smiled and said to me, "Little friend, this mushroom costs 7 yuan a catty. How much catty do you want?" "Aunt, I only need to buy half a catty." I think: 7 divided by 2 equals 3. 5 yuan, 20 MINUS 3. 5 equals 16. 5 yuan. I thought about it and gave my aunt a note of money from 20 yuan, reminding her to call me at 16. 5 yuan. I went to the meat department again and saw an uncle selling meat, so I asked, "Uncle, how much is a catty of meat?" "10 yuan a catty." "Then I'll buy a catty." On second thought: 16. 5 minus 10 equals 6. 5 yuan. I play 16. 10 yuan in 5 yuan was given to Uncle.
When I came out of the market, my mother saw that I had both meat and vegetables and 6. When I was in 5 yuan, I smiled and said to me, "Learn to buy food!"
Through this test, I feel that there are many mysteries of mathematics hidden in our lives, and the ability to learn mathematics is really important. And don't be proud. You should study hard and master more math skills in order to apply what you have learned and solve the problems around you.
Math diary, a fourth-grade student, 1 1 ate steamed buns at a special steamed bun shop this morning. The steamed buns there are really delicious, and everyone is full.
At this time, my father asked me a question: "My father and son started eating steamed buns at the same time. The son ate one and a half steamed buns and the father ate six steamed buns. If my son eats three steamed buns, how many steamed buns can my father eat? " As soon as the topic came out, my first thought was to judge from the sum of the numbers they ate, that is, one and a half plus six is seven and a half, and seven and a half MINUS three is four.
Half. Dad said it was wrong. So, I turned to consider the difference in the number of buns eaten by father and son, which is still wrong. At this point, I am a real Zhang Er monk-I am completely at a loss, and I don't know how I could be wrong.
Dad reminded me: "Let's start with the time relationship." I also cleverly changed the shape of this question. This change suddenly dawned on me and I recalculated: Is it okay for my son to eat one and a half buns, my father to eat six buns and my son to eat three buns? This other kind of idea came out at once. It takes twice as long to eat three steamed buns as it takes to eat one and a half steamed buns, so dad eats twice as many steamed buns as six, that is, twelve. It can be concluded that dad eats steamed buns four times as fast as his son. At this point, my father suddenly said, "This shows the speed at which our father and son eat!" " "The whole family laughed.
Math diary, Grade 4 12 Today, I went to the market to buy food with my mother. Mom said, "I will test you today. Will you buy a dish you like?" My mother gave me 20 yuan to watch my performance. "Make sure the task is completed." I said confidently.
So, I walked and watched, and came to the vegetable area. At this moment, I saw an aunt selling white and tender fresh mushrooms. I think: the leftovers at home can be cooked with mushrooms. So, I asked the aunt who sells vegetables: "Aunt, how much is a catty of mushrooms?" Aunt smiled and said to me, "Little friend, this mushroom costs 7 yuan a catty. How much catty do you want?" "Aunt, I only need to buy half a catty." I'm thinking: 7 divided by 2 equals 3.5 yuan, 20 minus 3.5 equals 16.5 yuan. After thinking about it, I gave my aunt a note of money from 20 yuan, reminding her that she still needs to find me 16.5 yuan. I went to the meat department again and saw an uncle selling meat, so I asked, "Uncle, how much is a catty of meat?" "Then I'll buy a catty." I want to subtract 10, which is equal to 6.5 yuan. I handed the 10 yuan in 6.5 yuan to my uncle.
Coming out of the market, my mother smiled and said to me, "Learn to buy food!" " When she saw that I had both meat and vegetables and 6.5 yuan in my hand.
Through this test, I feel that there are many mysteries of mathematics hidden in our lives, and the ability to learn mathematics is really important. And don't be proud. You should study hard and master more math skills in order to apply what you have learned and solve the problems around you.
Math diary 13 When the fourth grade just entered the third grade, he felt that mathematics was getting more and more difficult, and he was afraid of taking exams and doing problems. My parents always encourage me to learn math well, which is very useful and interesting. At first, I was always skeptical. I suddenly wanted to eat curry rice at noon on Saturday, and my father took me to Le to buy curry. When I arrived at the supermarket, my father said to me, "Before I went out, I grabbed a handful of change, and there were two 1 cent. Can you calculate it well in the future, buy less things and use this 20 cents? " Hearing that my father wanted to play math games with me, I immediately became interested and immediately replied, "Great, just to practice my brain!" " "I looked everywhere in the supermarket and finally found the counter selling curry. After careful observation.
There are four kinds of curries on the shelf, which are mushrooms, beef, chicken and mushroom beef. Because all three of us like meat, we refused mushrooms first. Look at the price, beef and chicken are both 5. 6 yuan, beef with mushrooms 5. 8 yuan, this beats me. I calculated carefully that two packs of mushroom beef can have 60 cents change, plus 1 pack of beef has 60 cents change, and the balance of three packs is exactly 20 cents. I quickly selected three packs of curry and handed it to my father, who nodded with satisfaction. On the way home, I said to my father, "It turns out that mathematics is used in accounting. It seems that mathematics is really useful in life! " "
Math diary, Grade Four 14 Today, Teacher Zheng doesn't know what medicine is sold in the gourd? Actually gave us a "79.0438+0 < () < 79.438+0", that is to say, how many decimal places can be filled in brackets? Some people say ten, some people say nine, and others say ... At this moment, the bell rings and the teacher has to say, "This question is a bit difficult. Let's go back and think about it."
I thought to myself: Is this a difficult question? But what is the answer? There is only one answer? Question marks keep popping up in my mind. How many decimals can be filled between one decimal and another? what do you think? ……
I looked out the window, hoping to find some inspiration. Suddenly I saw a tricycle go straight, but turned a corner at the crossroads. My eyes lit up! Thought: Why do I always think in one direction? You can also turn a corner like riding a tricycle! Take 79. 1 > () > 79.05438+0. Each number has only one phase.
8 when the difference is 0.0 1, 0.00 1, 0.000 1 ... There are countless correct answers. I was ecstatic and jumped three feet for joy.
When doing math problems, it is often impossible to think from one angle. If you want to "beat around the bush", you can think from another angle or multiple angles, which can better solve math problems.
Math diary, Grade 4 15 My family is a warm family of four, with my father, mother and brother. My family lives in the west unit of a beautiful family in Huaguang Road, 100 square meter, with two rooms and two halls.
My home is a living room of 20 square meters. There are three mahogany sofas in the living room, one for three people and the other two for one person. In front of the sofa is a coffee table with a length of 1.2M and a width of 0.6m There are many fruit snacks on the coffee table, which I like very much.
In front of the coffee table is a flat-panel TV with a length of 0.95M and a width of 0.5M m. After finishing my homework, I turn on the TV and watch my favorite cartoon-Pleasant Goat and Big Big Big Wolf.
On the left of the living room is my bedroom. The floor of the bedroom is 5.6 meters long and 4.2 meters wide. My bedroom has a desk with many books and review materials, and a 14 inch red notebook computer.
There is a piece of wood crawling up and down on the bed behind the desk. Bed length is 2M, width1.2M, bed length is 2m, width1.2m.. When I am tired, I will lie in bed and rest. At night, I will sleep peacefully here until dawn.
Out of the bedroom is a rectangular kitchen. Whenever I am thirsty, I take out my drink from the refrigerator. The refrigerator is 0.8 meters long and 0.5 meters wide, which is very small.
I like my home very much. My father, mother and brother all love me very much. I grew up happily in this family.