Interesting math story. I am in a hurry.

1. One day, the little white rabbit went shopping and met uncle goat on the way. I saw Uncle Goat frowning and sighing. The little white rabbit was puzzled and asked, "Uncle Goat, why are you unhappy?" "alas! Forget it. I went to the vegetable shop opened by the fox and bought 2 kilograms of celery at a price of 8 cents per kilogram. I gave him 2 yuan, and he only got 4 cents back. You see, this is the bill: the more I think about it, the more wrong it is, but I can't find anything wrong. Please help uncle calculate quickly! " The white rabbit was furious after reading the bill. "You sly fox! I must cure you. Uncle goat, you wait here and I'll settle accounts with him. "

The white rabbit came to the vegetable shop opened by the fox and said, "Boss, how much is celery 1 kg?" Give me two kilos! "The fox said with a smile," celery is 8 cents per kilogram. "After weighing, the white rabbit handed the money to 2 yuan, and the fox took out a pen and paper, ready to settle accounts. The little white rabbit said, "I'll do the math!" " "A pen and paper grabbed the fox, as he said, vertical column. "Eighty cents per kilogram is 0.8 yuan. I'll give it to 2 yuan, and 0.8 yuan to 2 yuan. It is listed vertically: 4 yuan wants to pay back the money. " Hearing this, the fox let out a scream, "How did you work it out? ! You only gave me 2 yuan, but you want to get back 4 yuan and ask me for 2 pounds of celery! " The little white rabbit took out Uncle Goat's money and threw it in front of the fox. "How did you calculate it for Uncle Goat!" "The fox bowed his head helplessly.

The white rabbit asked the fox for extra money for Uncle Goat, and happily followed Uncle Goat home. Children, can you tell me what's wrong with the above two accounts?

Bad Fox and Triangle

The hen hatched four chicks. She was happy and worried. Happily, all four chicks are jumping, which is really pleasing; The worry is that the bad fox will steal the chicken.

In order to prevent the bad fox from stealing chickens, the hen found many boards and sticks and built a flat-topped cabin. Mother hen thinks that she is not afraid of bad foxes when she has a house.

Late at night, the fields were quiet. In the moonlight, a black shadow quickly ran near the cabin.

"Bang, bang!" The knock at the door woke the hen. "who?" Asked the hen.

"It's me, it's my husband's chicken. Open the door quickly. " A very ugly voice is answering.

The hen thinks: No! Husband's chicken is out of town, and it will take many days to come back. Besides, this ugly voice is not the voice of the husband chicken at all. The hen said loudly, "You are not an old hen, you are a bad fox. Go away quickly!" " "

When a bad fox can't be fooled, he shows his ferocious face. He snapped, "Give me the chicken! Or I'll tear down your house and eat you all! "

Although the hen was afraid, he said, "No, no, no! My chicks can't be eaten for you. "

The bad fox was furious and shook the flat-topped wooden house hard. Four chickens were so scared that they hid under the hen's wings. After shaking for a while, the frame of the house tilted. There was a big crack between the roof and the wall. A big fox's paw came in and caught a chick and ran away.

At dawn, birds fly around looking for food. A cry alarmed them.

Little yellowbird asks, "Hen, why are you crying?"

The hen cried and said, "I built a flat-topped wooden house to prevent bad foxes from stealing chickens." Who knows that the flat-topped wooden house is not strong, so the bad fox pushed it three times and two times. The bad fox caught a chick, blare ... "

The woodpecker said, "Little magpie can build a house. Please ask him to help you build a strong house!" " "

After a while, the woodpecker invited the magpie. The magpie said, "I can only build nests. Where can I build a house?"

"What shall we do?" Everyone is worried.

The magpie said, "Once I was in a big tree, I heard several builders say that the triangular roof is the strongest."

The woodpecker said anxiously, "Who has seen what a triangle looks like?"

The magpie made a triangle from three branches.

Everyone said, "Let's build it like this."

Some birds are holding branches, some are holding mud, woodpeckers are pecking holes in the wood, and magpies are tying up all the wood with twigs. When the sun went down, a new house with a triangular roof was built.

In the evening, the bad fox came again. This time, he said nothing and shook the wooden house desperately. Strange, why can't this wooden house shake tonight? ! The bad fox shook it again with all his strength, but it still did not move.

It's almost dawn, and the bad fox said bitterly, "Even if I spare you now, I'll come back tomorrow." If you dare to come out, I will eat you! " "

Early in the morning, the bird saw the hen worried about guarding the cabin again.

Little Shan Ying asked, "Mother hen, your cabin is very nice. What are you worried about? "

The hen said, "the triangular roof is safer, but we can't always stay in the house!" The bad fox said he would catch the chicks as soon as we came out. "

The lark said, "I have a good idea. We helped mother hen fence the house and install a wooden fence door to get in and out. Isn't this a good way to prevent bad foxes? "

Everyone said it was a good idea, so they started to build a wooden fence together. They also sharpened the top to prevent bad foxes from jumping in. Finally, install a rectangular wooden fence door.

At night, the bad fox really came again. He saw the baby chicken jumping around in the fence, drooling. The bad fox turned around the wooden fence twice and found that it was the easiest to break the fence door. He shook the wooden fence door with two claws. As a result, the rectangular door became a parallelogram, revealing a gap. The bad fox jumped in. I'm afraid it will be a disaster if the hen doesn't bring the chick to the house quickly.

The bad fox is gone. The little magpie flew in and said, "Rectangular doors are easy to deform. Nail a board diagonally and turn it into two triangles, which will be much stronger. "

The lark said, "We can't always guard against bad foxes. We should do this ... like this. " Everyone was very happy and busy for a while before leaving.

The bad fox came quietly again without eating the chicks. He went straight to the wooden fence door and shook it vigorously. Hey, why can't you shake it this time? The fox shook it with all his strength and fell into the trap with a splash. The bottom of the trap was covered with triangular spikes, and the sly fox died.

The hen said happily, "triangles are really useful!" "

3. The ambition of serving the motherland-the story of Hua

As we all know, Hua is a self-taught world-class mathematician. He only has a junior high school diploma. Because a paper was published in Science magazine, it was appreciated by mathematician Xiong Qinglai. From then on, North China went to Tsinghua and began his mathematics career.

65438-0936, recommended by Professor Xiong Qinglai, Hua went to Cambridge University in England to study. Hardy, a famous mathematician in the 20th century, has long heard that China is brilliant. He said, "You can get a doctorate in two years." But Hua said, "I don't want to get a doctorate." I just want to be a tourist. " "I came to Cambridge to study, not to get a degree." In the past two years, he has devoted himself to studying the theory of heap-based prime numbers, published 18 papers on the problems of Waring, altruism and Chigodbach, obtained the famous Fahrenheit theorem, and showed the outstanding wisdom and ability of China mathematicians to the whole world.

From 65438 to 0946, Hua was invited to give lectures in the United States and was hired as a tenured professor by the University of Illinois. His family also settled in the United States, with a house and a car, and their life was very comfortable. At that time, many people thought that Hua would never come back.

The birth of the new China touched China's love for the motherland. 1950, he resolutely gave up his comfortable life in America and returned to his motherland. He also wrote an open letter to China students studying in the United States, urging them to return to China to participate in socialist construction. In his letter, he revealed a childlike heart that loves China: "Friends! Although Liangyuan is good, it is not the hometown of longevity. Go back to Xi ... For the sake of the nation, we should go back ... "Although mathematics has no national boundaries, mathematicians have their own motherland.

Hua returned from overseas and was warmly welcomed by the party and people. He returned to Tsinghua campus, was appointed as the head of the Department of Mathematics, and was soon appointed as the director of the Institute of Mathematics of China Academy of Sciences. From then on, the real golden age of his mathematical research began. He has not only made remarkable achievements that have attracted worldwide attention, but also enthusiastically cared for and trained a large number of mathematical talents. He devoted a lot of efforts to the research, experiment and popularization of applied mathematics.

According to incomplete statistics, Hua * * * has published important mathematical papers 152, 9 mathematical works and1/mathematical popular science works for decades. He was also elected as a foreign academician of the Academy of Sciences and an academician of third world scientists.

From junior high school graduation to people's mathematician, Hua has gone through a tortuous and brilliant life path and won great honor for his motherland.

4. From one to one hundred

Gauss has many interesting stories, and the first-hand information of these stories often comes from Gauss himself, because he always likes to talk about his childhood in his later years. We may doubt the truth of these stories, but many people have confirmed what he said.

Gauss's father works as a foreman in a tile factory. He always pays his workers every Saturday. When Gauss was three years old in the summer, when he was about to get paid, Little Gauss stood up and said, "Dad, you are mistaken." Then he said another number. It turned out that three-year-old Gauss was lying on the floor, secretly following his father to calculate who to pay. The results of recalculation proved that little Gauss was right, which made the adults standing there dumbfounded.

Gauss often joked that he had learned to calculate before he learned to speak, and often said that he learned to read by himself only after consulting adults about the pronunciation of letters.

At the age of seven, Goss entered St. Catherine's Primary School. When I was about ten years old, my teacher had a difficult problem in arithmetic class: "Write down the integers from 1 to 100 and add them up! Whenever there is an exam, they have this habit: the first person who finishes it puts the slate face down on the teacher's desk, and the second person puts the slate on the first slate, thus falling one by one. Of course, this question is not difficult for people who have studied arithmetic progression, but these children are just beginning to learn arithmetic! The teacher thinks he can have a rest. But he was wrong, because in less than a few seconds, Gauss had put the slate on the lecture table and said, "Here's the answer! Other students added up the numbers one by one, sweating on their foreheads, but Gauss sat quietly, ignoring the contemptuous and suspicious eyes cast by the teacher. After the exam, the teacher checked the slate one by one. Most of them were wrong, so the students were whipped. Finally, Gauss's slate was turned over and there was only one number on it: 5050 (needless to say, this is the correct answer. The teacher was taken aback, and Gauss explained how he found the answer:1+100 =1,2+99 =10/,3+98 =/kloc-. A * * * has 50 pairs, and the sum is 10 1, so the answer is 50 × 10 1 = 5050. It can be seen that Gauss found the symmetry of arithmetic progression, and then put the numbers together in pairs, just like the general arithmetic progression summation process.

Three people have gone to live, and the owner has only one room left. Offer 30 yuan, three people each pay 10 yuan to stay. The price department came to check and found that the shopkeeper overcharged 5 yuan, because a room only needed 25 yuan a night, so he ordered the shopkeeper to return 5 yuan to three guests immediately. The shopkeeper gave the waiter 5 yuan money and asked the waiter to return it to the three men. When the waiter got the money, he thought, it is impossible to divide it equally if five yuan is given to three people. He simply took 2 yuan himself and left 3 yuan for the three of them to share. So he took 2 yuan and gave 3 yuan to the residents, and each resident got back 1 yuan.

Here comes the problem. At the beginning, each guest paid 10 yuan, and each waiter paid 1 yuan. In other words, each guest actually paid 9 yuan, and three guests should be 27 yuan. If you add 2 yuan taken away by the waiter, it is 27+2=29 yuan. So where did the remaining 1 yuan go?

6. A Shanghainese is shopping in the countryside. He asked the stall owner, how much is a pack of instant noodles? The stall owner said, 3 yuan. The Shanghainese said again, then bring me a pack. The stall owner gave him a bag, and then the Shanghainese asked, how much is your bottle of mineral water? The stall owner said, 1.50 a bottle. The Shanghainese said, well, exchange this bag of instant noodles for two bottles of mineral water. The vendor changed it for him. He took two bottles of water and wanted to leave without paying. The stall owner stopped him and said, pay! Shanghainese said, why give money? The stall owner said that if you take something, you have to pay! Mineral water money! ! Shanghainese say mineral water for instant noodles! ! The stall owner said that the money for instant noodles was not paid! The Shanghainese said, I returned the instant noodles to you! Then he left, and the stall owner didn't stop him. He always thinks there is something wrong.

7. A farmer selling crabs in the street, one kilogram of crabs 100 yuan, should have a turnover of 1000 yuan. At this moment, I passed a Shanghainese. The Shanghainese said, I like to eat crab feet, and my wife likes to eat crab bodies. I want to buy them separately. You break your feet and body and sell them to me. I want them all. So the farmer broke all his feet. At this time, Shanghainese said that the price of feet is cheaper, so I have to sell a catty of feet in 20 yuan and a catty of body in 80 yuan, which adds up to 100 yuan a catty, that's right! So, the farmer weighed the crab's feet, ***4 Jin, and took 80 yuan; Weighed the crab, weighing 6 Jin, and collected 480 yuan. The Shanghainese walked away with these crab feet and bodies. Farmers always feel that something is wrong, but they can't say it. After counting a little money, I found that a * * * sold not 1000 yuan, but 560 yuan.