In the math interest class, Teacher Zhuang brought us an interesting topic: During the Qianlong period of the Qing Dynasty, Emperor Qianlong went down to the south of the Yangtze River and met an old birthday girl. Upon inquiry, the birthday old man 14 1 year old, Emperor Qianlong gave the old man a pair of couplets: flowers bloom again, plus March 7. Emperor Qianlong asked Ji Xiaolan, the accompanying minister, to make a couplet, which was not difficult for him. His couplets are: Celebrate the ancient and the rare, celebrate the spring and autumn. The teacher said, "There is a math problem hidden in this couplet. Please calculate how old this old man is? " After listening to the teacher's words, I think "Hua Jia" means 60 years old, "Re-opening" means two 60 years old, "Sanqi" means 2 1 year old, and the first part is 60× 2+21=141year old; Ancient and rare means seventy years old, and "double celebration" means two seventies. "One more year in spring and autumn" means one more year, and the bottom line is 70× 2+1=141year. It turns out that there are also mathematical problems hidden in couplets! In fact, as early as ancient China, scholars often made couplets to recite things and metaphors, and they were very good at embedding some numbers in couplets, which made them not only literary and interesting, but also informative.

2. Pupils in the fourth grade math diary 300 words.

I read such a question in the primary school newspaper today. A snail climbed up the shaft wall from the bottom of 12 meters deep, climbed 3 meters during the day and fell 2 meters at night. How many days can this snail climb to the wellhead?

After seeing this problem, I think: climbing 3 meters during the day and falling 2 meters at night is equivalent to climbing only 1 meter every day, climbing 1 meter every day, and the well depth 12 meter. Isn't that 12 days to climb to the wellhead?

However, the answer is wrong.

How could it be wrong?

Oh, yes. Will you slide down when you climb to the exit on the last day? I can't help laughing at the thought. This question is so interesting! If you don't pay attention, let us give the wrong answer.

The correct thinking should be: climbing 3 meters during the day and falling 2 meters at night is equivalent to climbing 1 meter a day, but pay attention to 12-3=9, which means climbing 1 meter every day for the first 9 days, but on the day of 10, the snail climbed to the wellhead when it climbed 3 meters.

3. Pupils in the fourth grade math diary 300 words.

Today, I counted the number of pages and words in the book Free Travel in Thailand. I think it is difficult to count the number of words in this book, because every page of this book has at least one picture, and some are full pages of pictures. I browsed the whole book, and it is estimated that there are 500 words on an average page. I randomly counted 10 pages, then estimated the thickness of 50 pages according to the thickness of 10 pages, and then estimated the thickness of the whole book to be more than 3 pages, which should be more than 150 pages or even more than 20 pages. Then, the total number of pages in this book should be 50 * * * 3+20 = 6544. I estimated the number of pages and words. I turned to the last page, and sure enough, this book is 160, and my calculation is more accurate.

4. math diary 300 words in the fourth grade of primary school students

Today, I want to measure something at home. Let me measure the surface of the coffee table first: I took out a long meter ruler, put it in a small hole, and put a small board on my head to keep it from moving. Wow, the length is 1 m 1 decimeter, that is, 1. 1 m, the front of the refrigerator is 1.56 m, the TV is 0.7 1, the bed is 2.04 m, and the bedroom floor is 4.5m. If you put 65438 in, if you forget the decimal point in 1 meter, it becomes 1 1 meter. Wow, it is 10 times higher. I also want to see the height difference between my parents and me. I took out the meter ruler and measured the heights of my parents and me respectively: my dad 1.67 meters, the difference between me and my dad was 0.36 meters, my mom was second 1.57, and the difference between me and my mom was 0.26 meters. I want to grow taller than them quickly! The decimal point is also very important here, because if you remove the decimal point from 1.67 meters, it will become 167 meters, a giant in the sky, and even I will become a giant in the sky, 13 1 meter.

You can't ignore the problem, because if you ignore it, 100 will be done in vain. For example: 1.6+2.4, you can read it as 16+24=40, and for another example: 6.8-6.1(=)1.2-0.5, you can't see it clearly without looking carefully, which is easy to make mistakes! what do you think? Do you pay attention when you do your homework?

Now I know that the decimal point is very important in decimals, and it is also very important in life. If there is no decimal point, only integers, then the world will be chaotic!

5. Pupils have 300 words of math diary in the fourth grade.

Take 10 to buy books on the third floor of Trust-Mart today. I searched and found a book "Myths and Legends". When I saw the cover, I knew there were many wonderful stories in it. I decided to buy it, but when I saw the price, I was shocked again. It turns out that this book is 1 1 yuan. Feel the money in my pocket when reading this book. I'm really embarrassed!

The assistant aunt saw my embarrassment and asked kindly, "What's the matter, little friend?" I said shyly, "I want to buy this book, but I don't have enough money." She asked again, "How much money did you bring?" "Cai 10 yuan." I said. Aunt smiled and said, "Look at the price tag, little friend. It also says' Book sales are discounted, all of them are 10% off'." I asked, "What do you mean by' 10% discount'?" Aunt said: "It is to collect money at nine tenths of the pricing. For example, 10 yuan's books only accept 9 yuan."

I calculated that this book is only 9.90 yuan. "Yes!" I thank my aunt again and again.

I bought a satisfactory book today and learned knowledge. I'm so happy!

6. math diary 300 words in the fourth grade of primary school students.

Today, my mother gave me a profit and loss problem: the rabbit mother appointed a little white rabbit and a little gray rabbit to pick a certain number of mushrooms in a few days. White rabbits plan to collect 80 rabbits every day for the first five days and 60 rabbits every day for the next few days: Grey rabbits plan to collect 100 rabbits every day for the first three days and 70 rabbits every day for the next few days, so that they can rest for two days. How many days will it take the rabbit to finish the task? How many mushrooms do you want each person to pick? I thought about it and did it: first, I converted the plan of the little white rabbit into picking 60 rabbits every day, and then I picked less: (80-60) 5 = 100 (1). Then, I changed my plan to 70 rabbits a day, and then I picked more: 702-( 100-70) 3 = 50 (one). Then, according to profit and loss problem's calculation formula: number of copies = (profit+loss), the task to be completed by the rabbit is calculated (100+50) (70-60) =15 (days). Finally, according to profit and loss problem's formula: total amount = number of shares divided at one time+surplus, it is concluded that 805+(15-5) 60 =1000 (mushrooms) should be selected respectively.

I told my mother my idea of solving the problem. My mother praised me as a clever child and my heart was full of joy.