Math diary, grade five, 400 words.
Source: composition network _ junior high school | Author: composition network _ primary school time: 2013-10-0218:18
Math diary, grade five, 400 words.
The first article: math diary, Grade Five, 400 words.
Today, I came across such incredible data in a book: "A piece of paper with a thickness of 0.0 1 cm is thicker than Mount Everest after being folded in half for 30 times?"
This data is a bit "absurd" no matter how you listen to it. After all, it is a thin piece of paper. Can folding in half really surpass Everest? But many unexpected things may happen, so only through calculation can we uncover the mystery of all this.
Immediately I multiplied 0.0 1 cm by 2,1* * 30 times to get10737418.24cm.. Then, I converted the height of Mount Everest from 8848. 13 m to 8848 13 cm. By comparison, it is obvious that the thickness of paper folded in half for 30 times is indeed better than the height of Mount Everest, which is more than 10 times of the latter.
In fact, amazing data like this are everywhere in ordinary life, as long as you have a pair of eyes that are good at discovering.
The second article: math diary
Today, I followed my mother 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 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?" "10 yuan a catty." "Then I'll buy a catty." I thought: 16.5 minus 10 equals 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, study hard, master more math skills, apply what you have learned and solve problems around you.
The third article: math diary 400 words
I saw a topic "Mathematics in Life" in my math textbook today. The topic is: "China's population is about 654.38+0.3 billion. If we save 654.38+0 cents per person per day, if so, our country will save about 6.5438+0.3 million yuan. If primary school students need to save about 65438+ tens of thousands of dollars from grade one to college, then this money can be provided to 1805 children who are out of school and have no money to go to school. Wouldn't it be nice to give these money to those people? "
After reading the above information, I thought: many hands make light work. Suddenly I remembered, many hands make light work? Not good, because I thought about it: if this population of about 65.438+300 million wastes 65.438+0 drops of water, then a * * wastes about 65.438+300 million drops of water, then what do you think is 65.438+300 million drops of water?
I did a small experiment: I put 1000 drops of water under the tap and weighed them with a scale. The weight of 1000 drops is 200 grams. I wrote another calculation.
130000000÷1000× 200 = 260000000 (g)
260000000 grams =260 tons
I really don't know, it's shocking: if everyone uses one ton of water a month, then 260 tons of water can be used for two years. I went to ask my father, "How many kilowatt hours can a ton of water generate?" Dad said, "1 ton of water can generate 100 kwh of electricity." This means that 260 tons of water can generate 26,000 degrees of electricity.
Wow! I was shocked at once. 260 tons of water can play so many roles! So we should save all the water now, don't waste a drop of water, we should form a good habit of saving, and we can't waste any more.
Article 4: math diary, Grade Five
Math? What is mathematics? Mathematics is the eye of life; Mathematics is the crystallization of wisdom; Mathematics is the art of words.
I loved mathematics since I was a child, and I loved doing math problems, especially the wide angle of mathematics. Speaking of the wide angle of mathematics, I think of the problem of "chickens and rabbits in the same cage" this semester. I knew from the beginning that this problem must not be simple. But I am not intimidated by questions, which can stimulate my interest. I began to study this kind of problem and found the mystery at once. It turns out that this problem can be solved by many methods, such as hypothesis method, equation solution and list lattice. But I prefer the hypothetical method, because I think this method is very challenging and interesting.
We assume that they are all chickens, so according to the total number of chicken and rabbit heads, we can calculate how many feet * * * has under the assumed conditions, and then compare it with the original number of feet to see what the difference is, and then calculate the number of rabbits. I also found several quantitative relationships! ① Rabbit = (actual number of feet-number of feet per chicken × total number of chickens and rabbit heads) ÷ (number of feet per rabbit-number of feet per chicken) ② Chicken = (number of feet per rabbit × total number of chickens and rabbit heads-actual number of feet) ÷ (number of feet per rabbit-number of feet per chicken) And this kind of topic will always be in our daily life. 8 yuan/Ben, thick exercise book 1. 5 yuan/Ben, mom gave me a 9. I bought eight exercise books for 9 yuan. I knew at once that my mother was testing me! I can't let her look down on me. Using what I learned in class, I bought five thick exercise books and three exercise books.
From this incident, I understand a truth: mathematical knowledge is really everywhere in real life. As long as you are willing to explore, you will make more wonderful discoveries.
Article 5: math diary, a pupil.
One day, I was doing my math homework in the classroom. Then, I met a math problem that I couldn't understand. This math problem is: Find the volume of a cuboid. This question gives me two conditions. The cross-sectional area is 30 square centimeters and the width is 6 centimeters. I think: isn't the volume of a cuboid multiplied by its width and height? Why did the topic only give us the area and width of the bottom? I haven't thought about it for a long time and I don't know how to do it. So I went to ask the math teacher.
The teacher looked at the topic and told me that the cross section is the bottom area of the cuboid, and the width on the topic indicates the height of the cuboid. Now I finally understand how to find the volume of a cuboid. I learned a new knowledge. I'm so happy.
Later, when I saw such a topic, I was no longer afraid. I used the method taught by my teacher to distinguish the calculation method of cuboid volume from this kind of problem. This knowledge is really helpful to me. I used it to solve many problems that I couldn't understand. My heart is happier than anyone else, because I understand a truth: mathematics is full of mysteries, waiting for us to explore, make good use of and solve bigger problems and tests. The knowledge of mathematics is really endless, and we can't finish learning it. I hope to try my best to learn profound math problems.
Article 6: math diary's 400 words
Mathematics is an important subject, which is related to