The first article: math diary
I saw a puzzling math problem tonight. The topic is: 37 students want to cross the river. There is an empty boat at the ferry that can only take five people. How many times must they cross the river with this boat at least?
Careless people tend to ignore it? Empty boat? I just forgot to punt, so I can only take four people at a time. In this way, 37 people subtract one rowing classmate, leaving 36 students, 36 divided by 4 equals 9, and the classmate who worked as a boatman on the other side for the last time also landed 4, so it takes at least 9 trips.
Chapter 2: Don't waste water.
The other day, we went to my aunt's house to see my mother-in-law. By the way, school is about to start. Let's get together. Just then, the water stopped. On the day I left, I washed my hands, pressed the switch and left. As a result, I went to my aunt's house, played for a while and came home, and heard the sound of water rushing. I want to turn off the switch. Afterwards, I remembered that I forgot to turn off the switch that day. Since the water came, it has been flowing, flowing, flowing. We went for three days, and it took about 50 to 60 tons a day. So when we start, 60 times 3 equals 180 tons, about one ton of 2 yuan, and 180 tons times 2 yuan equals 360 yuan money. I wasted all 360 yuan in about three days! ! ! So sad! ! !
Children, you must not waste water like me. There is almost no water on the earth now. Please turn off the switch after washing your hands. Don't waste water!
Chapter 3: Mathematics in Life
There is a lot of mathematics in life, but I also found one. The winter vacation is coming, and winter vacation homework takes turns to distribute it. How much do I rewrite a day? I want to write two pages a day and four pages in English, because the number of pages in a day is 37, so 37/2= 18.5 (day) is about 19 days, while English is 6 1 614 =15. After a few days, I learned well. My father took me to Dicos. We wanted crispy fried chicken and we got a 20% discount card.
There are countless mathematics in life, waiting for you and me to discover!
Chapter 4: Preview is very important.
After math class today, the teacher arranged for us to preview division estimation.
What is a preview? Why does the teacher want us to preview? I came home with a surprise. Check the information and ask your parents. It turns out that preview is to read the contents of the book by yourself before learning a new lesson. Mark what you don't understand, and then listen carefully in class. ) In this way, you can have a preliminary understanding of new knowledge.
I previewed the division estimation curiously. Through the preview, I know the estimate of 538? At the age of 62, you can think of 538 as 540 and 62 as 60. So, 538? 62? 9。 It turns out that preview can help me clear away the obstacles in math learning and have a preliminary understanding of estimation. Can quickly accept new knowledge in class. Even if there is doubt, it can be easily solved.
Therefore, it is very important to preview before class, so we must develop the good habit of preview, because successful preview can make the lecture quality higher and the learning efficiency higher, so it is the golden key to open the door to knowledge.
Chapter 5: I love math.
Math, Math I love you, just as mice love rice. Do you know why I like math? Because mathematics is very attractive, I have always been deeply attracted by it.
I learned a new knowledge today, that is, the simple algorithm of addition and subtraction. After learning the simple addition and subtraction algorithm, my calculation speed is much faster and it is easier to learn to calculate. Give an example! For example: 367+498=? I just have to think like this: add up 498 to make 500, and then use 367+500. I found that I added 2 more, so I subtracted 2 from the total to get 865. And 796+295? I think so: 796 can be added to 800, 295 can be added to 300, one plus 4 and one plus 5, then the formula becomes 800+300-4-5= 109 1. Look, how convenient it is!
After learning the simple algorithm of addition, learning the simple algorithm of subtraction will be much easier. Such as: 483-299, hehe, you can find the way by gently moving your head. I'll take 299 and subtract it from 300, because it's 1, so just add 1 to the result, which is 483-300+ 1= 184, and the calculation is much simpler. However, I can warn you: it's best not to think about the minuend when doing subtraction, or you'll be in trouble!
Now, I like math more and more, because it makes me learn to calculate the results quickly, and math really makes me remember deeply!
Chapter VI: Mathematical Problems
I met another math problem today, and it took me a lot of effort 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.
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