Math diary 1 how to write it?
I just finished lunch at noon today and was working on an Olympic math problem assigned by my father. While writing, unfortunately, I met a difficult problem. I thought about it for a long time, but I didn't come up with an answer. I don't even have a clue. The question 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 read the question again and thought: this question is really difficult! Only knowing the product of two surface areas, the volume must also know the length, width and height, but there is no hint at all. How to solve this?
Just as I scratched my head, I suddenly wanted to use the equation I learned last semester to solve it, but I didn't understand the binary linear equation, so I had to ask my father for help. He taught me to use the idea of equation to solve it first, but I am not very familiar with this method of equation. So, he taught me another method-exclusion method: list the numbers first, and then exclude them one by one. First of all, we listed many prime numbers according to the requirements of the topic, such as: 3, 5, 7, 1 1 and so on. Then we started rejecting them. My father patiently accompanied me to find them. We found that there were only two numbers left: 1 1 and 19. 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, except the sum of the sides of the previous one. 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).
Later, I checked this problem with what I learned this semester: prime factor decomposition, and the results are exactly the same.
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.
How to write 2 in math diary
Today, my mother and I went to visit Nantang Old Street. We walked and walked. At this time, my mother said to me, "There are so many snacks here. Yingying will give you fifty dollars and let you make the decision today. " My mother gave me 50 yuan as soon as my voice dropped. I'm so happy!
With 50 yuan in my hand, I'm already thinking about how to use it reasonably. Those delicious foods that I wanted to eat immediately came to my mind: Tang Hua, sugar-fried chestnuts, durian crisp, watermelon juice ... I started to act. At this time, I saw my favorite sugar-fried chestnuts and ran over to ask the boss, "Uncle, how much is a bag of sugar-fried chestnuts?" "12 yuan." Uncle answered with a smile.
I thought to myself: 50- 12=38 yuan, I gave it to my uncle 50 yuan, reminding him to give me 38 yuan. My uncle complimented me on how fast I could count with my mouth while looking for change. I ate hot chestnuts and watched from side to side. At this time, I found another delicious watermelon juice, so I bought a cup of watermelon juice for 1 1 yuan without hesitation, and then returned the rest of 27 yuan money to my mother.
In a flash, colorful lanterns lit up in the sky. What a beautiful string! My mother gave me a question while looking at the colored lights: a string of colored lights, seven numbers of seven, and finally1; Count to nine, the last night; The number of five is just enough. How many lanterns are there on this rope?
I thought hard, and suddenly, I came up with an idea, which can be expressed as "dividing by 7 is less than 6, dividing by 9 is less than 6, and dividing by 5 is more than 0". Then 7x9x 1-6=57, test 57 divided by 5= 1 1+2, no; 7x9x2-6= 120, test 120 divided by 5=24, that's right. Finally, I told my mother the calculated answer 120, and then I told my mother the idea of solving the problem. My mother praised me for being great!
There are many mathematical mysteries hidden in life. As long as you study hard and are willing to explore and master more math skills, you can apply what you have learned and keep growing.
How to write 3 in math diary
Today, I have nothing to do. My mother was going to the street to buy food, so I went with her.
When I came to the vegetable market, I was bargaining here, which was very lively. My mother asked me what I wanted to eat. I said to buy some ribs, some winter bamboo shoots and some tomatoes to go home and scramble eggs. My mother said, "well, listen to my daughter today, but since you're here, you can help me settle accounts later." I said, "No problem."
We first came to the meat stall, and my mother asked, "How much is a catty of ribs?" The boss said, "18 yuan 1 kg." "I want two Jin." The boss weighed it and handed it to me. My mother asked me, "Do the math, how much is a * * *?" I think it's easy. 18 times 2 is not equal to 36 yuan. I readily replied, "36 yuan." My mother looked at me and smiled and said, "Correct answer, then I'll ask you again. I paid 100 yuan. How much should I get back? " I thought for a moment and answered "64 yuan". My mother patted me on the shoulder and said, by the way, let's come to the vegetable stall. My mother asked the aunt who sold vegetables to weigh a winter bamboo shoot and two tomatoes, and then asked me to work out the prices separately. I quickly figured out that winter bamboo shoots 23 yuan, tomatoes 8 yuan, a * * * cross to 23 yuan 8 yuan is equal to 3 1 yuan. The aunt who sells vegetables said, "This child is really capable and can settle accounts." I feel very happy. My mother and I went home with food. On the way, my mother asked me again, "How much did we spend on food today?" I slowly calculated in my mind that 36 yuan plus 3 1 yuan equals, and I answered my mother: "67 yuan." Mom said, "That's right."
At this time, I suddenly understood that mathematics has always been used in life. I must study more mathematics knowledge harder in the future.
How to write 4 in math diary
Whenever I walk into the campus, a very eye-catching sign will appear in front of me, which reads a sentence, that is, "learn mathematics in life and use mathematics in life." Yes! We can't live without mathematics. If we don't study math, we will make a lot of jokes.
Take an incident that happened to me two years ago. That day, I got up early, and my mother asked me to help her go downstairs and buy some breakfast. Then I went downstairs with five dollars. Go downstairs, buy breakfast, pay the money. The boss said, "These come to * * * two dollars and fifty cents. I'll give you two dollars and fifty cents. " Then he gave me the money. As soon as I saw it, I quickly said, "No, no! If you give me less than one yuan, you should give me three yuan and fifty cents! " After hearing this, the boss was stupid, hesitated for a while and said to me, "Little friend, you have miscalculated, that is, the 2.50 yuan you are looking for!" " "As soon as I heard this, I was in a hurry to defend myself:" Uncle, you have miscalculated, obviously it is three yuan and fifty cents! "The proprietress on the side saw it and shouted at me in an angry dialect:" Look at this child, he is not young, how can he not even know the most basic arithmetic! " Everyone who ate there laughed "ha ha ha". I looked at it and ran home sadly, telling my parents all the ins and outs of the matter. Mom and dad listened, and they also laughed and leaned forward and backward. I said angrily, "Even you laugh at me!" Dad quickly explained, "It's not that we love to laugh at you, but that you didn't understand and think about Jiao Yuan's score in mathematics. Then I'll ask you what $2.50 is. "
"A dollar."
"How much are those two twenties?"
"Four dollars, of course!"
Finally, I finally understood that my father's explanation was not serious. Since then, I have never made the same mistake again.
I will never forget this joke. It taught me a lesson, which will be imprinted on my mind forever.
Students, you must study math seriously. Mathematics is not that simple. After learning, you must remember: learn mathematics in your life and use it in your life.
How do you write 5 in math diary?
The mathematician Descartes once said this. "The universe is big, the particles are tiny, the speed of rockets, the cleverness of chemical engineering, the change of the earth, the complexity of daily use, and mathematics is everywhere." Indeed, mathematics is closely related to our lives, and the footsteps of mathematics are everywhere.
Last Saturday, the teacher asked us to go to some nearby places to investigate the mathematics in life. My deskmate and I went to the Postal Savings Bank to investigate the interest.
We came to the bank and began to investigate the bank interest. Now the Postal Savings Bank has raised the original interest rate by 10% to encourage people to deposit more, which is very attractive. The interest rate table is as follows:
Number of installments, central bank interest rate, postal bank interest rate
Three months 2.60% 2.86%
Six months 2.80% 3.08%
The annual interest rate is 3.00% to 3.30%
2-year 3.75% 4. 1.25%
Three-year 4.25% 4.675%
Current deposit: 0.35%
Seeing that the interest rate has been adjusted, should we take out the money we just saved and save it again, or keep it unchanged? In fact, there are hidden mathematical problems and many mysteries. Suppose: Xiaoming's father has saved 100000 for three years, just for one month. what should he do ？ The teacher said: interest = principal × interest rate × number of periods. According to "central bank interest rate", three-year interest plus one-month demand interest: three-year interest is10000× 4.25 %× 3 =12750 (yuan), and the sum of principal and interest is 1 12750, plus one-month demand. If the deposit is made after withdrawal, the interest of the current month will be calculated according to the previous month:100000× 0.35 %×112 = 29.17 yuan. Save it for another three years. The sum of due principal and interest is100029.17+100029.17× 4.675 %× 3 =14058 yuan. Therefore, it is better to take it out and store it. If it has been stored for half a year, do you want to transfer it? The first type: keep it for three years and keep it for another year. The calculation is as follows: three-year interest:10000× 4.25 %× 3 =12750 yuan, and the sum of principal and interest is 1 12750 yuan, and one-year current interest: 1650 yuan. The total principal and interest is about113144.625 yuan. Second, take it out. The current account of the previous year, the principal and interest are deposited at the new interest for three years. The calculation is as follows: the current account for the last six months: 100000×0.35%=350 yuan, and the sum of principal and interest is 100350 yuan. Three-year interest:100350× 4.675 %× 3 =14075.0875 yuan. The sum of principal and interest is14075.0875+100350 =114424.0875 yuan, so no matter how many years you deposit it, you'd better change careers.
After the interest investigation, we went to the township government to investigate some data of producers and income last year: in 2000, the town's fiscal revenue was 574,654.38+0.9 million yuan, social fixed assets investment was 936 million yuan, investment attraction was 65.438+0.996 billion yuan, and the total industrial output value was 3.3 billion yuan; The rural economic income was 2.28 billion yuan. The figures of these data are very large, which is not convenient to write, and it is difficult to remember an accurate figure, so mathematical approximation is used here. We recently learned the scientific counting method, and I think these figures can also be expressed by the scientific counting method: 574 1.9 million yuan = 5.74 19× 107 yuan, 936 million yuan = 9.36× 108 yuan,/kloc-0. This is also very convenient for counting.
Facts have proved that mathematics is not far away from us, and mathematics is around us. Mathematics is closely related to our life. As long as we carefully observe and think, we will certainly find mathematics, learn mathematics well and use mathematics well.
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