Qin Ke and Ning Qingyun walked around the nursing home with their secretary Zhang Yunxuan for a while, and soon approached a tree-shaded courtyard.

Before I walked in, I heard the sound of chirping children. There seemed to be a dozen children inside.

Seeing that Qin Ke was a little surprised, Ning Qingyun explained in a low voice: "My grandfather is bored here. In his free time, he tells stories to the children in the nearby orphanage."

Qin Ke nodded slightly. From this point of view, it seems that Grandpa Ning will not be too difficult to deal with.

Elderly people who like children are generally kinder.

When the three of them walked into the courtyard, they heard a girl ask: "Uncle, you said you graduated from the mathematics department of Yale University in the United States. Then can you tell me why everyone has to learn mathematics? Mathematics is so difficult, but it doesn't make sense.

No, I never learn well."

Then I heard a slightly deep man's voice saying: "Mathematics is the intermediary for human beings to understand nature. Any knowledge with laws and predictions is all based on the establishment of mathematics..."

"Tch, it's boring. What you said is the same as what my teacher said. I know it's useful, but it's not interesting at all. I thought you would say something different after you graduated from the United States! That's all.

, nothing more than that!”

The girl made a face, causing the children around her to burst into laughter.

Just at this moment, Qin Ke and the other three walked in and immediately saw the scene in the yard.

I saw a tall, thin old man sitting on a wheelchair. He was not tall, with sparse white hair on his head. His eyes were always squinted, and he was wearing thick black-rimmed glasses.

There was also an energetic old man sitting next to him. The old man seemed to be much younger than the old man. He was wearing a crisp suit and his gray hair was neatly combed. He was chatting and laughing with the old man.

There is a young man standing next to the old man in a suit. He looks to be about 24 or 25 years old. He is wearing a well-cut white suit and rimless glasses. He has a good appearance and gives people a gentle and cultivated feeling.

At this time, he was surrounded by more than a dozen children ranging in age from eighty-nine to thirteen or fourteen years old, asking questions. Their faces were a little embarrassed and embarrassed, and even a little bit angry.

A round-faced girl with a single ponytail and about the same age as Qin Xiaoke was obviously the instigator just now. While she was making faces at the young man arrogantly and proudly, she also encouraged other children to ask questions to the young man.

The old man smiled and did not interfere.

Another boy, the youngest, seven or eight years old at most, with a shaved head, asked: "Uncle, you are studying mathematics, may I ask a question? Isn't it right that a family of three needs six chopsticks to eat?"

The young man forced out a gentle smile and said, "Yes."

The bald boy smiled and said: "But I don't use chopsticks! The correct answer should be four chopsticks and a spoon!"

The children laughed again, and the girl with a ponytail curled her lips and said: "You are like this, and you still want to chase Sister Ning? We don't agree!"

When they heard the sound of footsteps, everyone's eyes immediately fell on Qin Ke, Ning Qingyun and the other three.

When a group of children saw Ning Qingyun, they immediately cheered: "Sister Ning! Sister Ning is here!" They all surrounded her with a roar.

When the old man in suit and the young man saw Ning Qingyun, their eyes lit up at the same time. The difference was that the old man's eyes were filled with appreciation and satisfaction, while the young man's eyes flashed with surprise and covetousness.

But when his eyes fell on the hands held by Qin Ke and Ning Qingyun, his expression suddenly turned ugly. However, he was extremely restrained and could barely maintain a smile.

The girl with a single ponytail suddenly jumped on Ning Qingyun. Ning Qingyun had to let go of Qin Ke's little hand and hugged the little girl: "Xiaoling, you have grown taller again."

"Hey, sister Ning, you are still so beautiful. We all miss you! We received the storybook you sent us last time, thank you!"

This little girl is not pretty, but she is quite cute with her narrow eyes when she smiles. A smile appeared on the corner of Ning Qingyun's mouth: "As long as you like her."

The children's attention was quickly attracted by Qin Ke next to Ning Qingyun. The girl with a single ponytail named Xiaoling rolled her eyes, hugged Ning Qingyun tightly, and asked Qin Ke with a straight face:

"Hey, why are you here with our sister Ning?"

The other children also stared at Qin Ke with scrutiny and vigilance.

Qin Ke squatted down, looked at Xiaoling eye level, and said with a smile: "I guess your expression and hairstyle must be because you want to imitate your sister Ning, right?"

This was the first time that Xiaoling saw a boy who was a few years older than her squatting down and talking so carefully. His equal and gentle eyes, his free and confident smile, made her feel a little better at once. This guy was better than

The "uncle" who just pretended to look at people through his nostrils all day is much better!

But she still said arrogantly: "You guessed it right! Sister Ning is our idol! Let me ask you, how is your academic performance?"

Ning Qingyun next to her wanted to speak, but Qin Ke smiled at her and motioned for him to solve the problem. Then he looked at Xiaoling and said, "My academic performance is not good. I am always one place behind your sister Ning. Hey, there is nothing I can do about it. Your sister Ning's grades are not good."

That’s great, I will always be number one in my grade.”

"Hey, of course our sister Ning is awesome!" Seeing Qin Ke praising Ning Qingyun, Xiaoling and other children looked proud.

But Xiaoling launched another "attack": "Oh, your grades are not good, how dare you stand with Sister Ning?"

Qin Ke smiled even more happily: "Because I, like you, regard her as an idol. You dare to hug her, why can't I stand with her?"

All the children blinked, thinking that it seemed reasonable, but there was something wrong, and they were all asked back.

Xiaoling thought for a while: "No, I just saw you holding Sister Ning's hand, right? You must want to chase Sister Ning! If you want to chase Sister Ning, you have to pass our test! Let me ask you, mathematics is so

It’s difficult, so why study math? It’s not interesting at all!”

This chapter is not finished yet, please click on the next page to continue reading the exciting content! This question was answered by the young man just now, and what came back was a burst of laughter from the children. At this time, everyone's eyes couldn't help but fall on Qin Ke.

Including the young man's vaguely hostile gaze, even the old man and Zhang Yunxuan looked at the high school boy with interest.

Qin Ke smiled and asked: "Your name is Xiaoling, right? You are in the first grade of junior high school this year?"

"Yes, don't change the subject, answer quickly!"

"Then let me ask you a question you must think you know." Qin Ke took out a piece of paper and a pen from his backpack, and drew two dots on the paper with the pen: "Xiaoling, how do you combine these two dots?"

If the dots are connected together, the distance is the shortest?"

"Do you think I'm stupid? I'm not good at mathematics, and I know that 'the line segment between two points is the shortest'." Xiaoling took the pen and directly connected the two points with a straight line that was not very standard.

"Then do you know why the line segment between two points is the shortest?"

Xiaoling was startled and said, "It's written like this in the book, and you can see it! Of course the curve is longer than the straight line!" The other children also nodded.

Qin Ke smiled again and said: "Did you know? This line segment axiom also has a very powerful origin."

He has been telling stories to his sister Qin Xiaoke since he was a child. When his expressions match his words, he easily gets the children's attention.

"In August 1900, the world-famous mathematician Hilbert proposed the extremely famous 'Hilbert's 23 Problems' at the International Congress of Mathematicians in Paris, which is known as the world's most difficult to prove

It is a mathematical problem. Until now, all 23 questions have not been proved, including the fourth question 'the shortest line problem between two points using a straight line'."

Qin Ke looked at Xiaoling and the other children: "The things you take for granted are unsolved problems in the world of mathematics. Are you surprised?"

Xiaoling waited for the children to be completely attracted and nodded one after another. This was really beyond their expectations.

"Although the mathematical community can only prove that this axiom applies to straight space, it does not affect its application. Our urban planning, road planning, even the design of railways and aviation lines, and even various precision machinery all apply this

Axioms to save manpower, material resources, and time. Do you think mathematics is of great use?"

"big--!"

"The most interesting thing about mathematics is that it is not only useful, but also interesting. Let's go back to 'the shortest line segment between two points'. If I say, the distance between these two points, if it becomes an arc, will be shorter

, do you feel very contradictory?"

A boy with a square face said: "Yes, the arc is not a straight line, which contradicts this axiom."

Qin Ke bent the paper, and the straight lines originally drawn on the paper immediately turned into arcs, and the distance between the two points suddenly became closer: "Look, is the shortest between two points a curve or a straight line?"

The children were all stunned.

"The original straight line can actually become an arc, and the distance between the two points becomes shorter. This is the most interesting thing about mathematics. Once its prerequisites change, the conclusion is completely different, and it can also be compared with other

The integration of disciplines has produced many interesting theories."

"For example, the 'time machine' in the science fiction movies you often watch is actually an extended application of 'the shortest line segment between two points', but at this time the Riemann curvature tensor of the space is zero, and the shortest line segment connecting the two points

Renamed geodesic, the 'time machine' is a 'closed time-like geodesic'."

Qin Ke reopened the paper and drew one dot as the sun and another dot as the villain.

"To give another application example, here is where we are standing, and here is the sun above our heads. Normally, the distance between us and the sun at perihelion is 146 million kilometers, even if we take the fastest rocket (the speed is

km/h), it also takes nearly 167 days to reach the sun."

"But if we use the 'warp space' that also extends from the 'shortest line segment between two points', the distance between us and the sun can be shortened, and the time of space navigation is also greatly shortened. This is because mathematics is obviously difficult.

But it’s also very interesting and charming.”

A boy said excitedly: "So, will all the magical technologies described in science fiction movies appear?"

"Science fiction movies are imagined by writers based on the current knowledge of mathematics and physics. Some are right and some are wrong. The significance of mathematics is to tell us what is right and what is wrong. Let me tell you a little trick.

When a coin is tossed upwards, does it have a higher probability of landing on heads or tails when it lands?"

Xiaoling raised her hand and answered: "The probability is the same! The teacher said it!"

"Correct! But the probability is equally high. That's just a book theory. In fact, if you flip a coin regularly with your thumb, the probability that the coin will still be facing up when it hits the ground is about

It’s 51%. Want to know why?”

The children said in unison: "Think!"

Qin Ke said with a smile: "If you want to know, you have to learn mathematics well. Even if you don't want to know the reason, if friends like me who have learned mathematics well know the result, you will be better than others when you toss a coin in the future."

That’s a little bit more winning rate, right?”

All the children also laughed: "Yes! Thank you, brother!"

Unknowingly, the hostility in the children's eyes when they looked at Qin Ke had completely disappeared, and they even became somewhat close to him.

Xiaoling bit her lip and said: "Now I admit that mathematics is indeed useful and interesting, but it is too difficult..."
To be continued...