Wanderer of the whirling world

Chapter 7 Two-handed ten-finger problem

Jia Zhiqing stared at Xin Ziqiu with unbelievable surprise in her heart.

This question is not difficult. Even if you use the most stupid method, calculate the powers one by one and add them up, you will always get the answer after some time.

But just after he finished the topic, Xin Ziqiu figured it out, and he didn't even need to calculate it, it was unbelievably fast.

No need to ask, the boy in front of him must have a very ingenious and wonderful algorithm to solve this problem.

Jia Zhiqing hurriedly asked for advice:
"How to get it?"

Xin Ziqiu smiled and said:
"This is simple, add one to the bottom, multiply the bottom, and then add half to the bottom. Just like three into one."

When it comes to mathematics knowledge, his level of ancient Chinese has improved to a new level.

The translation of this sentence means n multiplied by n+1, multiplied by n+0.5, and finally divided by 3.In this question, n is the number 14 of the lowest fruit.

This is exactly the formula for the sum of squares of continuous natural numbers in modern mathematics, also known as the solution formula for quadrangular cone numbers or pyramid numbers.

Jia Xian listened to Xin Ziqiu's solution, stroked his beard, and after careful consideration, there was a light in his eyes that he hadn't seen for a long time. He nodded and said:

"Great! It's amazing. According to this method, any square stack can be counted. It's wonderful!"

Xin Ziqiu smiled embarrassedly, showing the ancients the modern mathematics of 1000 years later, it must be very subtle, but in fact, it is nothing more than that.

When Jia Zhiqing saw her grandfather praising Xin Ziqiu, although she was very convinced, she still refused to give in. She carved another calculation problem on the ground with a short knife, and killed a few cockroaches.

Xin Ziqiu saw it, and his heart moved slightly. There are so many cockroaches in this place, which is a bit abnormal.

Looking intently at the ground again, what Jia Zhiqing wrote this time was a classic "Ten Fingers with Both Hands Question".

The topic roughly means this:
Every normal person has ten fingers, which can be straight or bent, and one finger can represent two different numbers.

Ask how many different numbers can be represented by all ten fingers of a person.

For example, if a person stretches all ten fingers, it can represent a number "0".

The thumb of the left hand is bent and the other nine fingers are straight, which means another number "1".

By analogy, according to the bending or straightening of different fingers, how many different numbers can be represented in total.

The answer is two to the tenth power, which is one thousand and twenty-four.

This problem is a classic permutation and combination problem in modern society, and many primary school students participating in the Mathematical Olympiad can solve it.

It's just that this is the Northern Song Dynasty 1000 years ago, so this kind of topic is very difficult.

In fact, Leibniz, the great German mathematician who created calculus, did not propose and solve this problem until hundreds of years later.

Without even thinking about it, Xin Ziqiu opened his mouth and answered:

"One thousand and twenty-four."

This time Jia Zhiqing wasn't just surprised, her almond eyes were wide open, her mouth opened and closed, she couldn't speak at all.

This question was extremely difficult at the time, and it stumped countless scholars and Confucians at that time. She herself was a conceited arithmetic genius, and she had to think hard for several months before she came up with a little idea, but she still hasn't figured out the solution.

Of course, if you use the exhaustive method, as long as you are careful, you will always get the answer, but for people like them, they must pursue a more concise, ingenious and meaningful solution.

Jia Xian had already worked out the answer to the question, but Jia Zhiqing was so angry that she never asked her grandfather for advice, she insisted on doing it herself.

Now that the problem that she had worked so hard on was solved in an instant by a young man who was not yet a weaker crown, this was beyond Jia Zhiqing's comprehension.

Indeed, even in a modern society where anecdotes and strange stories emerge endlessly, if a young man demonstrates to mathematicians how to decipher Goldbach's conjecture or Poincaré conjecture from scratch, there will be a lot of people thinking about it. He's about to be captured and sliced.

Such a whimsical plot can't be written in a fantasy novel, okay?

This time, not only Jia Zhiqing was surprised, but even Jia Xian lost his composure. He was stunned for a while, and suddenly asked:
"Xin Xiaoyou, are you a human or a fairy?"

Xin Ziqiu laughed loudly and said:

"This is not difficult, but the topic is contrary to ordinary people's thinking. As long as this is the case..."

He talked about the topic succinctly, which is all due to the fact that he often attends remedial classes on weekdays and tutors the students in Mathematical Olympiad.

Jia Xian admired:
"Xin Xiaoyou really has a beautiful heart. Your algorithm is a hundred times more refined than mine, and your explanation is also subtle, and it hits the point. I have studied spells for decades, and I seldom admire others. You are one of them."

Hearing this, Xin Ziqiu's heart was filled with joy, he was just an ordinary young man, but he didn't have the cultivation level of the eminent monks and old Taoists.

To be able to span several centuries and receive heartfelt praise from a famous mathematician in the history of mathematics is naturally very beneficial to him.

Although he knew in his heart that he had opened a cheating device and had nothing to be proud of, it felt really cool to pretend to be that!

He smiled slightly, and said with the appearance of an outsider:
"Small skills are nothing. If you two don't dislike them, I will tell you everything I have learned in the future when I have time in the future. Please criticize and correct me."

As he was talking, he suddenly thought that if modern mathematics was taught to the Northern Song Dynasty, it would definitely greatly increase the productivity at that time, and perhaps the entire human society would benefit greatly from it. I wonder if it will promote the change of the entire historical process.

Such a good thing, if you have the opportunity, you can really try it.

Hearing this, Jia Xian sighed softly.

Some people like to gamble, some people like to drink, and he is most obsessed with the study of arithmetic in his life.

Right now, this young man regards all kinds of problems as nothing, and he must have earth-shattering knowledge in his chest.In normal times, Jia Xian would definitely take him home and ask him for advice.

But at this time, he and his granddaughter had important affairs to attend to, so there was really no time for him to take care of them.

Jia Zhiqing was thoughtful, silent for a while, then suddenly raised her head, looked at Xin Ziqiu and asked, "Brother Xin, I have something to ask..."

Before she finished speaking, Jia Xian coughed and said, "Zhiqing, don't speak nonsense, our own affairs, don't make Xiaoyou Xin go to danger together..."

"But grandpa..."

Jia Xian's face darkened, and Jia Zhiqing was so frightened that she didn't dare to speak anymore.

Xin Ziqiu looked puzzled and asked:
"Mr. Jia, you have saved my life. If you have any difficulties, just ask. As long as I can help, I will definitely help you."

Jia Xian shook his head, sighed and said:

"Xin Xiaoyou is serious. Since Zhiqing mentioned this matter, I can't hide it. In fact, our grandparents and grandchildren came to Bianliang City in Tokyo this time. This matter requires the participation of some people who are proficient in spells. And the old man... this... is also considered to be well-known in the way of spells, so he was invited to Kaifeng Mansion."

"I didn't expect to meet Xiaoyou Xin by chance on the road. Xiaoyou is young and has extraordinary attainments in the study of arithmetic and mathematics. Zhiqing was impatient for a while, so she wanted to ask you to help. She is young and ignorant. I hope your Excellency will not be offended by Xiaoyou Xin's abruptness in the part of the exchange of shallow words and deep words."

When Xin Ziqiu heard this, he immediately became interested. On the one hand, he was curious and didn’t know what a great mathematician like Jia Xian needed to solve. On the other hand, he happened to be going to Bianliang City in Tokyo, so he would definitely not be able to follow them. If you get lost, there is a guide along the way.

So he said excitedly:

"Not abrupt, not at all, as long as Mr. Jia doesn't dislike the lack of knowledge of the younger generation, and I am willing to help, how about we go to Bianliang City together?"

Jia Xian smiled bitterly and said:
"Hey, little friend Xin doesn't know something. This matter is not trivial. It is not only very difficult, but also extremely dangerous. The lives of those involved are always in danger, and even if it is done, it will be of no benefit. Our grandparents and grandchildren owe Kaifeng government money My lord and Zhan Huwei have a big relationship, and I have no choice but to go and not help. But if you drag Xiaoyou Xin into a dangerous situation because of this, and cause you to lose your life, then this old man really has no conscience, and he will regret it."

As soon as he heard that his life was in danger, Xin Ziqiu lost his confidence, but he was a little embarrassed to refuse now that he had talked enough just now.

While he was hesitating, he suddenly heard Jia Zhiqing screaming in a shrill and terrified voice:

"Ah, look over there, what is that!"

　Without a domestic mobile phone number, there is no way to sign an electronic contract.However, the contract has been sent out, and the status of the contract will be changed next week. Book friends who want to invest should hurry up~

　　
　
(End of this chapter)