Click.

The wheels rolled, kicking up puffs of smoke and dust.

Xu Fenglei in the carriage looked at the young scholar in front of him with a curious expression.

"You are Li Chunfeng?"

He said with great interest,

"The one in charge of the Qin Heavenly Prison?"

This trip was on the order of Li Shimin to go to the palace to meet him.

Unexpectedly, there was a person on the way, and this person was Li Chunfeng, whom Xu Fenglei had always been interested in.

This, according to legend, is a 'heavenly official' who comes out once in 500 years, and if you take it seriously, you can be regarded as the ancestor of your former numerologist!

"The next official is Li Chunfeng."

Li Chunfeng's expression was a little restrained, and he bowed and said,

"I've seen Taishi Xu Gong."

"Xia Guan does also have the errand of Qin Tianjian, but he mainly serves in the Taishi Bureau, and he is a general."

Xu Fenglei bowed slightly.

"Oh yes, it's the Taishi Bureau."

He laughed,

"The Taishi Bureau is in charge of astronomy, geography, calendar-making, and history-revising. You can't do it without a genius. ”

"Brother Chunfeng, he is a talent that is rare to see in a hundred years!"

When Li Chunfeng heard this, he praised and waved his hand again and again.

"How dare you...... It's too much of a praise. ”

He hurriedly said,

"Xia Guan is just doing his own job, and he is not a genius."

"A character like Xu Gong is the real pride of the sky......"

He was a little flattered by this sudden compliment.

"Hahaha, I can't talk about it, I'm just lucky, I'm actually very good."

Xu Fenglei laughed loudly and waved his hand,

"Let's not be so polite, you and I are the same age, just be commensurate with brothers! I'm the one who hates this honorific title the most, and that honorific title adds to the distance. ”

"I heard that you have a deep study of Yi Li, and you are also very good at mathematics, and you are the first mathematician in the world."

"Boring all the way, why don't we discuss it?"

Li Chunfeng's eyes lit up.

He's not good at interpersonal communication, so he's a bit rushed, but when it comes to academic discussion, he's not sleepy!

"I have long heard that Xu Gong is easy to count everyone, and Chunfeng has been friends for a long time."

Li Chunfeng said,

"Don't dare to talk about it, and ask Xu Gong for advice."

He no longer calls himself a subordinate official, but he still uses an honorific title for Xu Fenglei.

After all, the two have just dealt with each other, and people are polite to you, you can't take it seriously, really call people Brother Fenglei, right?

He's not good at interpersonal interactions, but he's not stupid.

"Good ......"

Xu Fenglei nodded and asked,

"I have heard that you are good at observing the heavens to know the things of the world. I don't know much about the relationship between astronomy and Yili, and I've never observed celestial phenomena. ”

"This is my knowledge blind spot, can you tell me about it? If it comes to confidentiality, forget it. ”

Although it was Li Chunfeng who 'consulted' him, in fact, it was completely him who consulted Li Chunfeng.

Just kidding, people are heavenly officials who come out once in 500 years!

I am just a small minion in the area of numerology, at most, I can rely on the prophetic advantage of the traverser to make a straight break, and I am far worse than others!

Now that I have the opportunity, I naturally have to ask for advice!

"There is nothing confidential or unconfidential, if Xu Gong wants to know, Chunfeng knows everything."

Li Chunfeng smiled and groaned,

"Xu Gongke once heard that Fu Xi observed the heavens and the earth and deduced the innate gossip."

On this basis, King Wen wrote "Zhou Yi". At the same time, easy-to-learn works such as Lianshan and Guizang also emerged. ”

Xu Fenglei nodded.

These basic common sense, of course he knows,

"Therefore, celestial phenomena are the basis of easy learning, and can even be said to be the source."

Li Chunfeng said in a deep voice,

"But as time went on, since Zhou, more and more books on easy numbers have emerged, and they have become more and more complicated."

"The origins are becoming more and more blurred."

Therefore, I prefer to observe the heavens rather than the methods of divination, prediction, and inference derived from various sources. Because that's closer to the source, naturally, it's more accurate. ”

Xu Fenglei suddenly.

"I see, teachable, teachable."

He hurriedly asked,

"What kind of observation is the celestial phenomenon? And how do you connect celestial phenomena with human beings? ”

Now he looks like a poor student who is receiving make-up classes......

"Personnel, small things, too, have few changes, and can be inferred by ordinary judgments; State affairs are extremely complex and involve a lot, so it is necessary to use the celestial phenomena method. ”

Li Chunfeng patiently explained,

"Of course, some important people came into being, and their fates will naturally be linked to celestial phenomena."

"For example, Your Majesty, such as Xu Gong, you are all important figures in the Tang Dynasty, and there must be a celestial star to correspond. This is called the emperor star, the phase star, the general star, etc. ”

Xu Fenglei raised his eyebrows.

"I also have a corresponding nakshatra?"

He suddenly became interested and asked.

This is interesting, he is a time-traveler, and logically speaking, he should not belong to this time and space.

If there is a corresponding star, it means ...... When you come to Datang, it's also a certainty?

Thinking of this, a chill rushed to Xu Fenglei's heart for no reason, making him shiver.

"Naturally, there is."

Li Chunfeng said with a smile,

"Xu Gong has sprung up, and his momentum is like a rainbow, which should be a great help for the country."

Xu Fenglei raised his eyes and glanced at Li Chunfeng, seeing that his eyes were deep, and suddenly there was a feeling of discomfort that his underwear was being seen through, and he hurriedly changed the topic and said:

"Haha, borrow your auspicious words, borrow your auspicious words."

"Then Brother Chunfeng, please tell me about the specific steps of this celestial phenomenon? I'm interested! ”

Li Chunfeng retracted his gaze and nodded.

"Okay."

He said in a deep voice,

"If you want to say the law, you have to start with the root of Yi, there are three fundamentals."

"It's not easy, it's easy, it's easy." Xu Fenglei blurted out.

It's all the foundation of the basics.

"Yes."

Li Chunfeng said,

"The so-called is not easy, the sun, moon and stars, the operation of the heavens and the sky, eternal and unchanged, the ancients thousands of years ago, the sky that Fuxi saw thousands of years ago, and the sky we see now, are the same sky, this is not easy."

Xu Fenglei nodded again and again.

"Today's people don't know the ancient times and months, but this month used to be like the ancients."

He read,

"The sun, moon and stars have never been easier."

Li Chunfeng raised his eyebrows.

"Good poems, good sentences."

He praised,

"Xu Gong is still a literary poet."

Xu Fenglei smiled.

Writer? Poet thieves.

I won't tell you the truth, I will 'when the river moon shines at the beginning of the year, and who sees the moon at the beginning of the river's bank.' Life has been infinite for generations, and Jiang Yue looks similar every year', they all mean the same, but I'm embarrassed to take it out and show it off.

"The sun, moon and stars are not easy, but they will change."

Li Chunfeng said again,

"The moon is full and lacking, the stars are dark, and the fighting is turning. That's how they've changed. ”

"The frame is not easy, but the frame is easy, and this is like an image, just like a picture frame, you can draw a cat, you can draw a tiger, you can draw a dragon, you can draw a snake. The celestial phenomena are like cats, tigers, and dragons in the frame. Snake-like, ever-changing, it's all like. ”

"And with an elephant, you can infer from the elephant, and that's easy......"

“……”

Xu Fenglei listened to it as if he had been enlightened, and he was fascinated.

This Li Chunfeng really didn't hide his selfishness at all, and directly said the most fundamental essence!

In just half an hour, Xu Fenglei felt that he had grown by leaps and bounds!

"Brother Chunfeng, you rest for a while, I have to find a notebook to write down my feelings......"

Xu Fenglei took out a small notebook from his arms, and found a pen from the carriage, and said with a focused face,

"You wait for me, and then you'll talk to me later......"

Boom.

At this moment, he is already like a diaphragm, and his feelings are written in books, which is even more refreshing than taking a shower!

"Okay, Duke Xu, just take your time."

Li Chunfeng smiled lightly,

"Please lend me a piece of paper, it's a long way away, and I'm just working on the next problem that has been bothering me for a long time."

Cha.

"Take it, take it!" Xu Fenglei tore off two pieces of paper casually and handed them over with a pen.

"Thank you, Gong Xu."

Li Chunfeng took the pen and paper, sat opposite Xu Fenglei, and after drawing a few strokes at random, he also fell into deep thought.

The carriage was bumpy, but the two of them didn't feel anything, they were both immersed in their own world......

Half an hour later.

"Whew-"

Xu Fenglei threw down his pen and said with a comfortable face,

"Today is really listening to your words, better than reading a book for ten years!"

"The celestial phenomena are indeed mysterious, I have a first glimpse of the door!"

"Hahaha......"

He looked at the experience in his hand and laughed heartily.

turned his head to look, but saw that Li Chunfeng was biting the tip of the pen, his brows were furrowed, and he seemed to be in deep thought.

This scene made Xu Fenglei a little surprised.

Wizards like Li Chunfeng will also have things that they can't figure out?

He stood up, moved to Li Chunfeng's side, and looked at his piece of paper.

On the paper, a cylinder is drawn with a half-round lid, and on the far right, a ball is roughly drawn.

"Brother Chunfeng, what are you busy with?"

Xu Fenglei said casually,

"You're calculating?"

"Yes." Li Chunfeng exhaled lightly, shook his head and sighed, "I am measuring the size of the ball, according to the method proposed by Zu Xuan, I only need to ask for the size of the square cover, and the size of the ball can be obtained, because two things with the same cross-section at the same height must also be the same size, but why ......?"

Xu Fenglei almost fainted.

"What kind of high cross-section, messy I don't understand."

He said,

"Isn't it just asking for the volume of the sphere, which is very easy to do."

Li Chunfeng looked up sharply.

"Xu Guild calculated?"

He replied,

"Please advise!"

Xu Fenglei was a little baffled by his sudden appearance, but when he saw the look of longing in the other party's eyes, he also reacted.

This Li Chunfeng is an easy-to-learn master and a mathematician who loves mathematics!

The essence of easy learning is images and numbers, and it is impossible for people who are proficient in easy learning not to be interested in mathematics.

"Here, give me the pen."

Xu Fenglei took Li Chunfeng's pen and said,

"To measure the volume of a sphere, there is actually a formula."

"The formula is – V = 4/3πR to the third power."

Li Chunfeng was stunned; “……”

"What is V? What is π? What is R? What are these 3s and 4s? ”

His whole body was in a circle.

Xu Fenglei wrote this suddenly, he couldn't read a word!

"Uh...... These are all symbols. ”

Xu Fenglei helped his forehead, and this time it was his turn to patiently explain,

"V, which means volume."

"3 and 4 are relatively simple numbers, representing three and four, and the others are 0, 1, 2, 5, 6, 7, 8, 9, I have taught the prince them, and now I will teach you, this number will be much simpler, otherwise it will be too troublesome to use Chinese characters, too abstract, and not conducive to our mathematical research."

When Li Chunfeng saw this series of numbers, his eyes bloomed.

"Replace the man with a simple symbol one, two, three? This is indeed a feat! ”

He was pleasantly surprised,

"This is Xu Gong, you invented?"

"Uh...... I also learned it, and it was Tianzhu people who invented it. Xu Fenglei scratched his head, did not have the cheekiness to take the credit on himself, and said with a smile, "There are many religions in Tianzhu, there are Buddhism, Tianzhu Sect, and various sects often debate the scriptures, in order to be able to overwhelm each other, they need to use a huge number to show the strength of their gods, so ...... They are also well developed in arithmetic. ”

Arabic numerals were invented by Indians...... Well, I should be not mistaken.

"I see."

Li Chunfeng was amazed and said,

"To be able to create such a number must be a magical country."

"If you have the opportunity, you should communicate with the Tianzhu people."

When Xu Fenglei heard this, he couldn't help but laugh secretly.

A magical country? Then the kingdom of Ah San must be magical!

It's just that you can't think of it, there's nothing that the third brother can't do.

"And this π?"

Li Chunfeng looked at the paper again, pointed to the symbol, and said,

"What do you mean?"

"That's what pi means, you know for sure." Xu Fenglei said, "Liu Hui once used the method of cutting the circle to accurately reduce the pi to 3.1416, and Zu Chongzhi made the pi more accurate to 3,1415926 on the basis of Liu Hui!" Leading the world! ”

Li Chunfeng nodded again and again.

"I know this, it is recorded in the "Nine Chapters of Calculations".

He praised and sighed,

"Liu Hui and Zu Chongzhi are both immortal! Pity...... Mathematics has always been neglected. ”

"I've always felt that mathematics is actually very important, and it is closely related to everything in this world, ......"

Xu Fenglei raised his eyes slightly.

"You're right."

He is right,

"Mathematics is the foundation of all science and engineering."

"Only when mathematics develops, other things can develop together, so I have plans to vigorously promote mathematics and develop mathematics in Datang!"

"In this way, the country can progress!"

When Li Chunfeng heard this, he was immediately in awe.

"Xu Gong is far-sighted!"

He gave a thumbs up and said,

"If it can really be like this, it is the luck of Datang!"

Xu Fenglei grinned.

"When the time comes, I still need your help."

He patted Li Chunfeng on the shoulder and said,

"In my Chang'an Academy, there is a mathematics course, and there is a mathematics academy next to it."

"It's up to you to decide who is the dean! Brother Chunfeng. ”

Li Chunfeng: "?!" ”

"I ...... What can I do? He was shocked, and was about to excuse himself, but he was held down by Xu Fenglei. Datang, only you are a well-deserved mathematician! ”

Xu Fenglei Zhengsedao,

"You are the dean of mathematics!"

"Just do me a favor, and you don't have to excuse yourself!"

(End of chapter)