Composition: math diary

In our daily study, work and life, everyone will be more or less exposed to composition. Composition is a transition from internal speech to external speech, that is, from compressed and concise language that we can understand to developed and standardized grammatical structure that others can understand. Still at a loss for composition? The following are my collected compositions: math diary, welcome to share.

Composition: math diary 1 During the winter vacation, my father asked me to preview the math in the second volume of the sixth grade. I saw such a problem in the math workbook: the radius of the bottom surface of a cone is 8 decimeters, and the ratio of height to the radius of the bottom surface is 3: 2. What is the volume of this cone? Analysis: This is an application problem distributed in proportion. ...

I figured it out on this issue without reading the analysis, huh? I haven't learned how to calculate the area of a cone. Then how can I solve this problem? I sighed, ready to continue to watch the analysis, and then I thought, after this winter vacation, won't I be in the sixth grade? If I can't even do this problem, am I still a good student? Yes, I have to solve it myself.

I always build a model in my mind before this kind of problem, but I am very cautious about this problem for fear of making mistakes. I drew a perspective effect of a cone on the paper. Take a closer look, huh? Isn't this figure the same as a triangle if it is a plane figure? Isn't the cubic area of this cone 1 of the area of a cylinder with the same base and height? I am ecstatic. The original cone area is also quite easy to find! As long as you know the height and bottom area of the cone, can't you get it? Back to this question, its condition tells you the radius of the bottom, which is equivalent to telling the area of the bottom. It says that the ratio of height to bottom radius is 3: 2, which means that the length of bottom radius is two-thirds of height. Isn't that height just radius ×3÷2= height? Therefore, the height is 12 decimeter, the bottom area is 200.96 cubic decimeter, and the cone area is 200.96×12 ÷ 2 =1205.76 cubic decimeter.

"Wow, I finally solved it." I'm relieved. Through this question, I also found that in fact, there are many things in mathematics that are interlinked. It is not necessary to know all the calculation formulas. As long as you can integrate, the problem can be solved.

Composition: It is sunny in math diary on Sunday, September 26th.

Today, my mother and I went shopping. There are so many food stores on the street! My mother and I are dazzled. My mother started to pick, and she picked left, right, up and down. Finally, she finally picked a tomato that she thought was good in a vegetable shop. Tomatoes cost 2 yuan a catty. She bought 1 kg 9 Liang, and she gave the vegetable vendor 3 yuan. The vegetable seller gave my mother 1 point. She bought ribs again. The ribs are 5 yuan a catty, and she bought 2 Jin and 2 Liang. She gave it to 50 yuan, the sparerib seller, and 39 yuan, the sparerib seller. She bought potatoes again. Potatoes are 1 yuan 1 kg. She bought 3 Jin and 3 Liang. She gave them to a vegetable seller, 5 yuan, and gave her 1 Yuan 70. She bought bean sprouts again. These bean sprouts cost 65438 yuan. She bought five taels and gave them to the vegetable seller 1 yuan. The change is fifty cents. She bought ginger again. Ginger 2 yuan 1 kg. She bought 1 kg and a half, gave it to the ginger seller 10, and got 9 yuan change. She spent 18.7 yuan on dinner.

Composition: math diary 3 met another math problem today, and it took great efforts to solve it. The topic is: there are 30 birds in two trees, and 4 birds fly away from the second tree first. At this time, tree A flew to tree B with three birds, and the birds on the two trees were just equal. How many birds are there in each tree?

As soon as I saw the topic, I knew it was a reduction problem, so I solved it by the method of reduction problem. But when I checked, I found something was wrong. I will do it again more seriously. I think there are as many as four missing, half of them are 13, and the restored B-tree is14; A tree is 16. The formula is: (30-4) ÷ 2 = 13 (only); 13-3+4 =14 (only); 30- 14 = 16 (only). The answers are: a tree 16 and b tree 14.

By solving this problem, I understand that no matter what I do, I should be careful, otherwise, even if I master the solution to the problem, the result will be wrong.

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

Composition: math diary 4 We have finished learning Unit 2: Surface area and volume of cuboids and cubes. In order to let us understand the concept of volume more deeply, the math teacher arranged a math diary for us to measure the volume of irregular objects.

After careful consideration, I finally chose to ask for the size of potatoes. My mother brought me a potato and said, "The potato has no shape at all. How can I measure its volume? " I confidently replied, "Nothing, I know what to do."

I first found a rectangular water tank and measured its length and width. Length 24㎝, width 17cm. Then I poured some water into the sink and measured the height of the water in the sink. The water is 5 cm high.

Next, I gently put a washed potato into the sink. After the water level stabilized, I measured the height of the water in the sink again. The height of the water was 5.5cm, and the last step was to find the volume of potatoes.

I listed the formula for finding the potato volume:

24× 17×(5.5-5)

=24× 17×5

=204 (cubic centimeter)

A: The volume of potatoes is 204 cubic centimeters.

When I listed the formula, my mother suddenly realized. I didn't expect mathematics to be so useful in daily life. This also reminds me of the allusions of Cao Chong's image. How to weigh an elephant that big? Clever Cao Chong thought of driving the elephant to a big ship, writing down the scale on the ship, and then loading the large and small stones on the ship one by one, and the ship sank bit by bit. Just now, when the ship sank on the scale, it stopped loading stones, and then measured the weight of the stones. The sum of the weights of the stones is the weight of the elephant. Cao Chong is really smart and an example for me to learn.

Learning math is very interesting. Just do the math experiment by yourself. It is good to use math diary's method to record the process of thinking about mathematical problems. I will stick to writing about math diary.

Composition: math diary 5 At noon today, I looked at a map of China at home. My father asked me, "Do you know which railway to take from Beijing to Shanghai?" I replied, "Take the Beijing-Shanghai line." Dad asked again, "Do you know how many kilometers there are on the Beijing-Shanghai line?" Can it be measured by map? "

Looking at the winding lines on the map, I am a little confused. How to measure them? I tried it with a ruler first, but no, the bending place is not easy to calculate; I used the rope again, it was too thick, and it was not allowed. At this time, I saw my mother sewing clothes, so I used cotton thread and I measured it with my father. First, put the cotton thread along the beijing-shanghai railway line, cut off the redundant part, and measure the length of this cotton thread with a ruler as 15cm. Dad said, "What is the scale of the map we want to see at this time? I looked at it and it was 1: 9000000 ". According to this ratio, I calculated that the length of the Beijing-Shanghai line is 1350km, in order to test our measurement. I asked my father, why are the two sets of data different? Dad said, "We measured it accurately, and it is normal to have a little error. After all, we measured it on the map with cotton thread. "

Composition: math diary 6 "100,200,300,400,500, haha, rich, rich, I got a commission of 525 yuan this year! Plus last year's full 20xx yuan! " I'm happy to say.

What investment should this money make? Buy stocks? The risk is too great! At home? No, you can't have money! At dad's house? No, no. Last year, he helped me save 1 000, which turned out to be the share capital for buying TV. He also threatened me that I wouldn't watch TV without investing, and he couldn't get the money. I, a "little TV fan", had to invest obediently. Nothing can be saved with him this year.

Just when I was worried, my mother came up with a good idea. She gives 1000 yuan every month, and my father gives 400 yuan money every month. I only take 1 ,000 yuan (total 1, 500 yuan) for one year at a time, and we will share the interest earned equally. This is really a good thing, I only make money.

I asked my mother doubtfully: Is what you said true? What you said is true. Really? Mom smiled and nodded. I was afraid that my mother would go back on her word, so I quickly took out 100 yuan from the box and handed it to my mother.

So, how much interest can I get? (Ha ha, this is what worries me most. ) My mother and I found an interest calculator with zero deposit and lump sum on the Internet. I entered the numbers as required-

Ah! The net interest is 166. Where is 73 yuan? Here comes my question again. If I only save 100 yuan every month, how much interest can I get? I forgot again:

Ah! Only 1 1. 12 yuan! Not as much as the score above! So how much money can you get for nothing? I picked up a pen and calculated it carefully: 166. 73÷2— 1 1。 12=72。 24 yuan. Haha, I am so happy to get more than 70 yuan! This deal is profitable!

Composition: math diary 7 "What time are we going to have a barbecue tomorrow?" I saw two cousins whispering to each other. And I overheard it and quickly shouted, "I'm going too!" " I'm going too! "Every time I think of these two cousins, I readily agree!

I'm so happy that I don't know whether to make peace or not. It's a jump of three feet!

That night, we went shopping at Wal-Mart! There are abundant barbecue foods here, such as fresh mutton, delicious chicken legs and wings, snow-white rice cakes and tender sausages. We put our favorite foods into the shopping cart one by one! A careful calculation actually has 100 yuan! Just then, my cousin's uncle and aunt called and said they wouldn't go tomorrow. Something had happened! At this time, we will put it back for them. It's also quite cost-effective, saving 40% of the money (about 40 yuan's money).

The next morning, we came to Korean pine xx! As soon as we arrived at the gate, a middle-aged man began to entertain us warmly and led us to his barbecue! We quickly found a stove and finished it! At this time, the middle-aged man came over: "It is said that a stove costs 25 yuan, and the money for adding coal accounts for 20% of the stove money (5 yuan) at a time." He said with a smile. So big cousin took 30 yuan money from her pocket and gave it to him.

At this time, we accidentally found a "hollow bamboo boat" floating on the water, so I quickly asked my sister to go boating! Although a little timid, my strong curiosity has swallowed it up!

So, the big cousin asked the boss, "Do you need money for boating?" "Yes, yes!" I chimed in at a side. "No need!" I'm so happy! Take off your shoes and socks! Get ready to row. But my sister has to accompany me!

This rowing process can be described as twists and turns! "Sister, the sense of direction is really bad!" Sister, your skills are very good. This noise can be said to be accompanied by the whole process of rowing! But in the end, we managed to reach our destination!

After eating the delicious barbecue food, we're going to help this sister calculate her fortune! So, we once again "climbed" to "wait for the sky", which really exhausted our physical strength.

My sister came to the fortune teller's office, and the master said to donate 10 yuan for social morality, but my sister donated 20 yuan. Soon, the signboard came out! "26, that's not bad!" The master said while touching his beard. If you go in the future, just donate 50%. "Oh," my sister said politely. "You." The master said a lot, but my sister kept smiling. It seems that this sign is good!

In this way, I spent a happy half-day in Akamatsu xx!

Composition: math diary 8 Everything in life is inseparable from mathematics. As long as you are good at observation, you will find that mathematics cannot be separated from you. After studying the knowledge of proportion for six years, I deeply realized that mathematics has brought us many benefits.

It's a sunny afternoon. My brother and I have an appointment to meet at 2 o'clock in the forest park, and then we will go to the zoo to play together. After arriving at our destination, we had to buy a map of the park, because this was our first visit to the zoo in Forest Park. After I got the map, my brother crept up to me and grabbed it. I have no choice but to restrain my unreasonable behavior towards this "little naughty boy" Then my brother solemnly said to me, "Brother, today my guide will take you to see the lion!" " "At this time, I thought to myself: I hope it won't be the opposite!

Then my brother took me everywhere like a headless fly. After about an hour, I finally couldn't help it. I shouted, "What are you doing? I'm exhausted. Why haven't I arrived yet? " I took the map back directly, and it suddenly dawned on me at first glance that it was my pushy brother who made up figures and interpreted the scale of the map as 1: 5000 as 1 cm representing the actual 5000 cm. "Well, learning a skill is really important! If you are as self-righteous as your younger brother and don't study hard, the consequences are often self-defeating! " Then, according to what I learned, soon, we came to the lion. Look at my brother's envy. He's begging me to accept him as an apprentice!

Knowledge is the key to success, students, study hard! Let's create a better tomorrow with our own efforts!

Composition: math diary 9 Today, my mother went down to weigh herself. Her weight is 49.3kg, and her height is neither short nor too high, 162cm. Mom said, this is a math problem. You can write it on the math problem. I listened to my mother and posted her height and weight. Then, I saw another number, 18.8. I asked my mother what the middle row meant. Mom said it was an index calculated by height and weight, indicating that mom was in normal shape. I finally understand that these three are my mother's indicators.

Many problems in our life can be explained by mathematics. For example, my height is 120 cm, and my brother is 80 cm, so I am 40 cm taller than him. For example, age, grandpa is 62 years old and brother is 2 years old. Grandpa is 60 years older than his brother. For example, the temperature is so low during the Chinese New Year. One day, the lowest was only 5 degrees Celsius, and the highest was only 10 degrees Celsius, shivering with cold. For example, today is Saturday, February 20th, 20xx, and it's 8 o'clock in the evening. For example, in counting rankings, my mother took 10430 steps a day, ranking sixth among friends. There is still a turnover. My brother's bathtub is full of water. After putting my brother in, the water came out. How much water does it take to fill it up after taking my brother out, that is to say, it is the place occupied by my brother after going in. There is also a younger brother who drinks milk from a bottle. How many milliliters are written on the bottle, and which number is reached after the milk is filled, it means how many milliliters of milk there are. My brother drinks 180ml every time. Hee hee. There is so much math in my life that I should study hard.

Composition: On the day of math diary 10, the teacher wrote such a topic on the blackboard: two pens and a ballpoint pen * * 16 yuan, two ballpoint pens and a pen * * *1yuan. So how much is a pen?

After writing, the teacher said, "Give you 10 minutes." I quickly lowered my head and began to do the problem. I thought and thought, but I still couldn't figure it out. It's been four minutes. I'm as anxious as a cat on hot bricks. I'm afraid other students can do it, but only I can't. Wouldn't it be a shame to be criticized by the teacher on the spot? How I wish a beautiful fairy could tell me how to do this problem now! In a blink of an eye, more than two minutes passed. I secretly looked around at my classmates. I saw some of them thinking seriously, some staring at the topic, and some looking around like me.

The teacher walked around and came back to the podium and said to us, "You can try to change the words into formulas!" " "After hearing what the teacher said, I quickly wrote two formulas on paper. 2 steel+1 yuan = 16 yuan; 1 steel +2 circle = 1 1 yuan. My eyes lit up and I was secretly happy. Isn't the difference between 16 and 1 1 more expensive than a ballpoint pen? I thought it would be worked out soon, so what should I do next? What's the use of this five? I'm really happy to have nothing. I can't park here. I'm not happy for nothing! I am prone on the table. The teacher seemed to see through my mind and came up to me to remind me that you can imagine buying a pen by assuming. What the teacher said made me feel suddenly enlightened: if I don't buy this ballpoint pen, the boss will give it back to me, 5 yuan. Three ballpoint pens need 6 yuan, and each ballpoint pen needs 2 yuan.

I solved such a difficult problem. It turns out that as long as you think more, the olympiad will become very simple.