Math diary 1, during the fourth grade math activity month, the competition was held at 24 o'clock in our grade. At that time, I often played with my mother until 24 o'clock.
Once, our cards were 7, 8, 4, 8. It suddenly occurred to me that if there is 4, there must be 6, that is, 8/8= 1, 7- 1=6, 4×6=24. My mother smiled and said to me, "There is another way." I thought about it and suddenly had an idea: 7×8=56, 4×8=32, 56-32=24. Mom asked again, "What about 4, 10, 10, 1?" I think, if there is 4, there must be 6, but what if 6 can't be found? Mom said: Don't go into a dead end. It suddenly dawned on me that multiplication was replaced by addition: 4× 1=4, 10+4+ 10=24.
My mother smiled and said that I know everything, I am smart, and I am very happy.
Counting 24 o'clock often can improve my calculation ability. Let's have a try!
Students of Grade 2 and Grade 4 in math diary ate steamed buns at the 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 and a 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 made me suddenly realize and recalculate: the time for my son to eat one and a half steamed buns is six, and the time for my son to eat three steamed buns-this flexible idea comes out, and the time for eating three steamed buns is twice as long as that for eating one and a half steamed buns, so the number of steamed buns eaten by my father is twice that of 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.
Grade four math diary 3 finished her homework early this morning. When my mother saw it, she came over and told me to play a game with you! ""good! " I readily agreed.
Mother brought a round cardboard and fixed a rotatable pointer in the center of the cardboard with a nail. The cardboard is divided into 24 grids on average, and the number 1-24 is written in each grid. "Mom, what are the rules of the game? Say it quickly! " I said impatiently. "The rules of the game are simple, that is, when the pointer goes to an odd or even cell, the next number must be added. If it adds up to an odd number, I win; If the sum is even, you win. " Mom said with a smile.
I saw that the rules of the game were very simple. I played for more than a dozen times in a row, but I couldn't beat my mother every time. My mother smiled. "Why is it always singular?" I asked my mother puzzled. Mom said, "Think for yourself!" So, I racked my brains to think, and finally reminded me of the formula that the teacher once said: odd+even = odd. Now I can see that if the pointer points to the odd number, then the next number must be even; If the pointer points to an even grid, then the next number added is odd, so no matter where the pointer points, the number added is odd. Mom won with this rule.
In the world of mathematics, there are many wonderful laws. As long as we learn math well and make good use of it, it is everywhere!
Math diary, Grade 4 Today, my mother and I went to the market to buy food. 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 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 20 yuan's money to remind her that 16 still has 5 yuan and she still wants me. 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." I think: 16, 5 minus 10 equals 6, 5 yuan. I gave it to my uncle 16 and 10 from 5 yuan.
When I came out of the market, my mother saw that I had both meat and vegetables and 6 or 5 yuan in my hand. She smiled and said to me, "Learn to buy vegetables!"
Through this test, I feel that there are many mathematical mysteries hidden in our lives, and it is really important to learn mathematical skills. 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.
When math diary was in the fourth grade and the May 4th grade, our math teacher organized a math group. Up to now, our math group has a whole year's history. The members of our math group are: Chen Junfeng, Wang Siyu, Zhu Zhengyi, Zhu Ziqi, Zhang Tiancheng, Li Mengya and me. Every week, a person will give a question in the group. Let's do it. So, on Friday, we will comment collectively. Through such a math group, I learned a lot:
1, because the five questions given each week are of different types, some will, some will not, some have studied, and some have not. What I have learned can help me to consolidate my previous instructions. If you haven't learned it, take it out and learn it.
If I want to do a problem by myself, I may only come up with one or two methods at most, while seven people in our math group will do it together, and there will be at least seven methods. So the math group has cultivated my spirit of finding problem-solving skills in various ways.
Because our math group has a discussion every week, everyone has to talk about it, and my oral expression ability is not good, so I call this opportunity not only to finish the problem seriously, but also to think about how to explain it to them. In this way, I exercised my oral expression ability.
4. Let me know the gap between myself and some good classmates through the explanations of good classmates in the math group, thus giving me the motivation to study hard and try to catch up with them.
This math group has given me so many valuable things, isn't it?
My mother and I went to the mall to buy clothes during the May Day holiday in math diary. However, I think the price there is very strange: does saying "buy 100, get 100" mean that 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 have to go to the mall again to make a serious investigation or consult Miss Liu to see what she has, because I know there is still a lot of math knowledge that I still don't understand.
With a happy mood, I came to the school to ask Mr. Liu a math problem. Mr. Liu said, "In fact, some of them are above 100, such as109,200,189 ..."
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. " Teacher Liu praised me for my willingness to ask questions. I am welcome to ask more questions in the future.
Math diary Grade 4 Grade 7 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.
Math diary Grade 8 and Grade 4, at noon today, I was doing the winter vacation homework of Mathematics. Unfortunately, when I was writing, I met a very difficult problem. I thought about it for a long time but I didn't come up with an idea. The problem is this: there is a cuboid, the product of the front and the upper two areas is 209 square centimeters, and the length, width and height are prime numbers. Find its volume.
I saw it and thought: this question is really difficult! We only know the area of two faces, and the volume must also know the length, width and height, but there is no hint at all. How does this start?
Just as I was scratching my head, my mother came. My mother first taught me to use the idea of equations to solve, but I am not very familiar with this method of equations. So, my mother taught me another method: first list the numbers and then exclude them one by one. First of all, we listed many numbers according to the requirements of the topic, such as: 3, 5, 7, 1 1 and other prime numbers, and then we began to exclude them. Then we found that only 1 1 and 19 were left. At this time, I thought: one of these two numbers is the length of the common side of the front of the cuboid in the question; One is the front of the cuboid, divided by the sum of the lengths of other sides (both are prime numbers). So, I began to tell which number these two numbers were.
Finally I got the result, which is 374 cubic centimeters. My formula is: 209 =11919 = 2+11× 2×17 = 374 (cubic centimeter).
I am happier than anyone to solve this problem. I also understand the truth that mathematics is full of mysteries, waiting for us to explore.
Math diary Grade 9 students saw an interesting math problem today, which is a math problem of traveling. The students must have done this math problem! The topic is this: someone is walking west to east along a small straight route parallel to the railway. At this time, a 546-meter-long train came from behind. The man measured that the whole train passed 42 seconds, during which time he walked 84 meters. What's the speed of this train?
After reading the topic, I found it difficult. People and trains are moving, and not much data is given. So, I find it difficult. I just think this line is actually a problem of catching up with the rear of the car and people. At first, the distance difference between them must be the length of the car. Time for the train to pass = time for catching up. It's very simple, which can be simplified as the train running on the highway for 42 seconds. This makes it easy to calculate the speed.
546+84= Length of this part =630. According to the distance ÷ time = speed, the next one is 630÷42= 15, so the train speed is 15 meters per second. Students, have you worked it out? Isn't math interesting?
Before math diary 10 in the fourth grade, I always felt that learning to find the least common multiple was boring, and it was really annoying to deal with the problem of finding the least common multiple of 1 1 2 all day. I have always felt that it is useless to learn this knowledge in my life. However, one thing changed my view.
That was not long ago. Grandpa and I took the No.2 bus to the Youth Palace. Just as the bus was about to leave, 1 the bus just started at the same time as us. At this time, grandpa looked at the two cars in front of him and suddenly smiled and said to me, "Zequn, grandpa has a question to test you, okay?" I answered confidently: "OK!" "Then listen carefully. If the 1 bus runs every 3 minutes and the No.2 bus runs every 5 minutes, how many minutes does it take for the two cars to leave at the same time? " I paused and said, "Grandpa, your question still needs one condition: the starting point of bus 1 and the starting point of bus 2 are in the same place."