On Saturday afternoon, I finished my homework and had nothing to do. My mother gave me a question: "Do you know the characteristics of multiples of 2?" As soon as I heard it, I immediately replied: they are all even numbers. "What are their characteristics?" Mom asked again. "Their units are all 0, 2, 4, 6, 8." Mom said, "You are really something. Do you know the multiple of 4 and the characteristics? " Now you have me stumped.
So, I found some multiples of 4 and found that their units are also 0, 2, 4, 6, 8, so I told my mother this rule. But my mother casually said a number, which overturned my discovery. Mom told me to keep watching, but I couldn't find it left or right. Mom reminded me: Look at the last two digits of these figures. I observed these figures according to the tips my mother gave me, and suddenly it dawned on me.
The original multiple of 4 is characterized by the fact that the last two digits of a number are multiples of 4, and this number is multiples of 4. Then, I found some numbers to try, such as: 437,37 divided by 4 = 9... 1. According to the law, 437 is not a multiple of 4. Then I divide 437 by 4 = 109... 1, which is consistent with this feature. I found another number, 1024, 24 divided by 4=6. I found that 1024 is a multiple of 4. I verified it again by division: 1024 divided by 4=256, so 1024 is a multiple of 4. I happily told my mother about this discovery, and my mother nodded with satisfaction.
I found this. Students might as well give it a try.
Math diary Grade Four Composition 2 65438+1It was cloudy on Wednesday, October 20th.
misunderstand
In the fourth grade, there was a problem called "wrong solution". Let me give you an example: When Wang Chen used the remainder to calculate the division, he misspelled the dividend 17 1 7, and the quotient was 2 less than the original, but the remainder was exactly the same. What are the correct divisors and remainders?
This problem is actually very simple: 17 1 misspelled as 1 17, and the quotient is 2 less than the original, then the difference between1-17 is the divisor. Now that the divisor is found, it is simple. The topic says that the remainder is the same, and I divide the wrong dividend and the correct dividend by divisor. If the remainder is the same and the difference between the two quotients is 2, then the topic is done correctly. Formula: (171-117) ÷ 2 = 27; 17 1÷27=6……9; 1 17÷27=4……9; 6-4=2。 The remainder is the same, and the difference between the two quotients is also 2. A: The correct divisor is 27 and the remainder is 9.
Wrong solution is really fun!
It's a drizzly Tuesday in math diary. I went to school with an umbrella and suddenly found the study garden on the first floor surrounded by many classmates. Curiosity immediately drove me to run over and have a look. Take a closer look, and with a "wow", there is a new topic in the wide angle of mathematics! No wonder it attracts so many students to see it! I got into the crowd and saw this question written on it:
A person wants to cross the river by boat. He only has a boat and three things: a chicken, a dog and a basket of vegetables. You can only take one thing across the river at a time. When people are not around, dogs eat chickens and chickens eat vegetables. How can I ensure that the three things I bring are intact?
After reading the topic, I thought about it. ...
I had a brainwave, and the answer was that dogs can't eat vegetables. They can send the chickens first and then send them back empty-handed. Considering that chickens can eat vegetables, bring them back, take the dogs and vegetables together instead, and finally bring them back. Yes, this is the answer. I smiled sweetly.
It's nice to have a wide angle in mathematics. I will definitely come here often in the future.
On the fourth day of math diary's fourth grade composition, 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.
Math diary's fourth grade composition 5 The first book "Harry Potter" price 19.5 yuan, 19 1 page. 19.5 ÷191≈ 0. 1 (yuan), one page is about 0.1yuan, and this book has been published 139 1500 copies. If all of them are sold, the profit can be1391500×19.5 = 27134250 yuan!
The second book, The Chamber of Secrets, sold in 22 yuan, with 203 pages. 22÷203≈0. 1 1 (yuan), the price of the second book is more than that of the first book 1 cent. This book has been published 127 1500 copies. The proceeds from all the sales are1271500× 22 = 2,793,000 yuan! .
The third book, Prisoner of Azkaban, costs 26.5 yuan, with 260 pages. 26.5÷260≈0. 1 (yuan). The price of the third book is the same as that of the first book, which is less than that of the second book 1 minute. This book has been published 127 1500 copies. The income from all sales is1271500× 26.5 = 33,694,750 yuan!
As a result, the second page has the highest price.
Math diary Grade Four Composition 6 This morning, we had an interesting Olympic math class. "Ding ..." The teacher came into the classroom with a big smile on her face. The classroom suddenly became quiet. The teacher said to us, "Let me test you a question first: the quotient obtained by dividing two integers is 12, the remainder is 26, and the dividend, divisor and quotient remainder are equal to 454. What is the divisor? " I read it again, two ... "... after I got the question, I thought: How can I find the divisor of this question without any divisor? But recalling that teachers often say that drawing line segments is a magic weapon to solve application problems. Why don't I try? So, I began to draw: first take the divisor as a multiple, the dividend is 26 times more than the divisor, and then draw the quotient and the remainder. Oh, it's a matter of the times. The formula is: (454-12-26) ÷ (12+1) = 390 ÷13 = 30.
I think: we have learned the method of calculating with X. Let me write out the formula of the text first. Divider × quotient+remainder+divisor+quotient+remainder =454, then let the divisor be X, and the formula is: x×12+26+x+12+26 = 454. I subtract 12 and 26 first, then I leave the dividend and divisor, and then because there is a remainder in the dividend. I want to subtract 26, so the dividend is equal to 12. The divisor is 30. Expressed by the formula, it is: x×12+26+x+26+12 = 454.
x =(454— 12—26—26)÷( 12+ 1)
X=390÷30
X = 30。
I finished both methods at one go. Everyone gave me a approving look.
My heart is full of joy. This course is really interesting.
Today, I waited patiently for my father to buy wine at the gate of the community. Suddenly, the security guard spoke and said, "Little friend, it's Arbor Day soon. We may plant trees in Haiqinyuan Community. May I ask you a question? " I was shocked at that time, and the security guard wanted to ask me questions! Uncle Security then asked me, "We want to plant 18 trees, both sides. How many trees should we plant on each side? " I quickly replied: "9 trees." Hearing this, the security guard happily said to me, "Little friend, you are so smart!" " "
After a while, my father came back and the security guard gave me a big compliment in front of my father. I was flattered to hear that.
Oh, so this is the division taught by Teacher Zhang! I can also do formulas.
18÷2=9 (tree)