On 19 May, the Battle of Qiantang lasted for another 16 days, but the imperial army did not advance an inch, and the number of people killed under the city walls had risen to more than 20,000, and countless people were wounded.

Such a casualty ratio was the greatest loss suffered by the Chu army since the Third Northern Expedition, so the edict issued by Zhongshu Province gradually became severe. Zhongshu Province represents the emperor, Xiao Yushu's heart is panicked, but war is not child's play, the emperor's edict and reprimand cannot break through a fortified city like Qiantang, if you want to win, you have to rely on the soldiers' lives!

Perhaps, it will depend on a little luck.

The night rain is misty, and the city of Qiantang is still standing in the distance!

A few fast horses galloped into the barracks, and some people were already waiting to hold the reins of the horses and lead the people to the tent of the Chinese army.

"Xu You meets the general!"

After Xiao Yushu was in a handsome position, he wrote something on the official document, raised his head when he heard the sound, his eyebrows were in the sideburns, his eyes were calm, his clear and three-dimensional face was sharp and angular, revealing indescribable coldness and heroism, only the hair was sprinkled with a little early snow, and the vicissitudes of life were inexplicable, but it added a bit of mystery and charm that only mature men have.

"You're Xu You?"

"It's down there!"

Xiao Yushu looked at Xu You seriously, suddenly smiled, and said, "I've heard of your name a long time ago, but I didn't expect that the first time we met was here." ”

Xu You said neither humbly nor arrogantly: "General Xiao's name, I often heard people mention it when I was young, and I can see it today, and I am fortunate to have three lives!" ”

"Do you often talk about me?" Xiao Yushu put down the brush in his hand, leaned back and leaned back on the cushion made of white tiger skin, put his hands into his sleeves casually, and said: "I must have used my twenty years of experience of not entering the fifth grade to sharpen my skills, what do you say, but are you still those clichés of 'when you are young, big may not be good'?" ”

He smiled freely, and was not ashamed to be a negative teaching material in the world's mouth. Xu You admired this kind of demeanor of seeing through the world, and said: "Everyone's Tao is different, there are many small masters in the world, but there is only one general Zhengdong who can quell the rebellion of the white thieves!" ”

Xiao Yushu was stunned for a moment, then laughed, stood up and walked to Xu You's side, patted him on the shoulder, and said, "Someone once comforted me and said that Yixing Xu You is just a vulgar martial artist, far from being comparable to when I was a teenager. People in the world are so ignorant that they only look at their skins, but they don't know that the subtle spirits are beautiful, and they are far from being mundane. ”

Xiao Yushu was the most optimistic young martial arts genius before Xu You, but after all, he wandered outside the mountain gate of Wupin, and he couldn't get a glimpse of the mystery of the little grandmaster. After Xiao Yushu, Xu You became his successor, so he was often compared by others, one old and one young, so there was a wonderful connection.

"Sit!"

The two sat opposite each other in the tent, Xiao Yushu didn't say too much greetings, went straight to the point, and said, "Gu Fujun strongly recommended it, saying that you have a strategy to break the enemy?" It is necessary to know that there is no joke in the army, if there is, it is true, and if there is none, don't talk nonsense! ”

Xu You said in a deep voice: "How dare You test the general's military law? Dare to ask the general, what is the biggest crux of the reason why Qiantang is difficult to capture? ”

Xiao Yushu did not despise Xu You because he was young, and after thinking about it seriously, he said: "The city is strong!" ”

"The city walls?"

"Exactly! If we talk about the number of troops, I have 150,000 people, and Du Mingyu has a maximum of 50,000 capable warriors, and the rest are mostly coerced people, so there is nothing to worry about; In terms of combat power, just 2,000 sword warriors are enough to defeat the white thieves, not to mention tens of thousands of Chinese troops and 100,000 Fuzhou soldiers; When it comes to armaments, I have abundant food and grass, and I have excellent swords and armor, and I am far above the white thief. If you fight in the field, you can win a battle, and if you have other cities, you can already go down in one go. However, Qiantang City was built by Du Mingyu at any cost like an iron wall, and the regulations chased the imperial capital of Jinling, unless the city was besieged for a long time, and its food was exhausted, otherwise, it would be difficult to conquer in a short time! ”

Since ancient times, siege warfare is the most headache in all wars, the battle of Handan in Qin and Zhao, the battle of Shule City in Han and Hungary, the battle of Yubi in the Eastern and Western Wei Dynasty, and even Zhang Xun guarded Suiyang, Zhu Wenzheng guarded Hongdu, Yu Qian guarded the capital, and then to the famous Battle of Diaoyu City, the weak brigade in the lonely city can be undefeated for a long time in the face of a strong enemy, and even turn defeat into victory.

If there is no city wall to protect it, no matter how united you are, no matter how fierce you are not afraid of death, there is no room for struggle in the face of absolute strength, so if you want to break the enemy, you must first break the city!

How to break the city?

Siege warfare has developed for thousands of years, and all kinds of siege methods and siege equipment have almost been played out of tricks, but in the era of non-firearms, or including the early stage of firearms, there is only one of the most powerful siege equipment in the real sense!

"I have something to help the general destroy the walls of Qiantang!"

"Oh?" Xiao Yushu's eyes burst out with a look of surprise, he was really choked by the difficult bone of Qiantang, almost suffocated with sadness, Xu You's words were like a bright light that broke through the dark clouds, even if it was ethereal, he couldn't wait to catch it, and said: "Say it quickly, if it can really work, I will ask the court for the first credit for you!" ”

Xu You didn't answer his question directly, and asked, "Will there be anyone with the army?" ”

The general supervisor is the official office directly under the imperial court, responsible for the administration of civil craftsmen, under the jurisdiction of the left school office, the right school office, the middle school office, the Zhen official office and the hundred works institute, of which the middle school office is responsible for the supply of boats, weapons, miscellaneous weapons.

"Yes, the lieutenant colonel signed the order to personally accompany the army, and there were ten supervisors, twenty wardens, and more than 300 craftsmen in each household."

"Please send the lieutenant colonel's best person to make equipment to assist me, and I will give the general an answer in seven days!"

Xiao Yushu can lead the army, and there is still a little bit of qi cultivation skills, seeing that Xu You sold the guanzi, he didn't ask anymore, and said, "Please, I'll go with you to meet Zu Xiao." ”

"Zu Hu?"

"Zu Xiao is a lieutenant colonel to sign the order, the word Xingzhi, my grandfather used to be a master craftsman, my father also served in the general as a supervisor, since he was a child, he has specialized in mathematics, searching the past and the present, and is the first-class arithmetic master today."

Xu You's head was hot when he heard it, his surname was Zu, and he was going to be a family, could it be Zu Chongzhi? However, he also knows that time and space are in order, things are people, and Zu Chongzhi cannot be Zu Chongzhi, but the law of historical development is always moving in an orderly manner according to some unknown road.

Seeing Zu Hu, he was thinner and shorter than Xu You imagined, his appearance was not good, his forehead was narrow, his cheeks were prominent, his nose was huge, but his eyes were extremely small, as if God had made a joke, so that an otherwise normal face was squeezed by the outside and moved the position of his facial features to a very inappropriate place.

It's a weirdo!

Not only does he have a strange appearance, but he also has a strange personality, seeing Xiao Yushu's top boss, today's celebrity, but he just looked up lazily, and then squatted on the ground intently and fiddled with a short wooden stick to calculate the chips.

Xiao Yushu was not annoyed, and explained to Xu You softly: "Xingzhi is obsessed with arithmetic, once he encounters a problem, he deduces it day and night, does not sleep or eat, we have seen a lot, so we don't feel strange!" ”

Xu You stood at the door, and the tent was full of arithmetic chips almost everywhere, as if he was studying difficult problems in arithmetic. He is not very proficient in the method of calculation, and he has only seen the frost fiddling with the calculation, but it is only a very simple four operations, and it is not yet up to the level of such a complex and profound level as Zu Qi.

The two waited for a long time, and Zu Hao finally threw away the calculation chip in his hand, sighed long, stretched out his foot and kicked, stirring up the dense calculation array into a mess.

Xiao Yushu introduced Xu You and said, "Xingzhi, this is Yixing Xu You, who has an important task and needs your help." ”

Zu Yu squinted at Xu You, snorted coldly, and said, "General, he is a yellow-mouthed child, what important things can I help?" The lieutenant colonel office is responsible for ordnance, and all the siege equipment that should be built has been built, if you still can't take the money, it is the matter of the general and the troops, and it has nothing to do with the lieutenant colonel's office! ”

Xu You secretly said badly, of course he was not angry because of Zu Xiao's rudeness and arrogance, a really talented person, a little quirk is harmless. I'm afraid that such non-respectful words will annoy Xiao Yushu and cause trouble, and that will be his sin!

Just thinking about how to remedy it, Xiao Yushu laughed and said, "You, it's just this mouth that doesn't spare people!" Saying that, he turned his head to look at Xu You, and said helplessly: "The temper of the lieutenant colonel's order, Wei Zhi has also seen it, what do you want to do, just talk to him directly, you don't have to go around in circles!" ”

Xu You's heart suddenly moved, and he said, "Could this be the circumcision?" ”

"Huh? Do you also know Liu Hui? ”

"Sages and sages, the kid doesn't dare not know!"

Zu Xiao sighed again, his expression instantly became strange, and said: "Liu Hui came from a humble background, and he has been down-and-out all his life, and there are very few people who know him. How can he dare to be called a sage and sage? ”

"The lieutenant colonel's order is wrong! Mencius said that everyone can be Yao Shun, Xunzi said that Tu people can be Yu, even if there is a beggar on the side of the road, as long as he wears Yao Shun's clothes, speaks Yao Shun's words, and does Yao Shun's things, it is Yao Shun. Xu Youlang said: "The so-called saint of the emperor lies in the royal pole and dominates the people, and the benefit is only one life; The so-called sage of Confucius and Mencius lies in educating and enlightening the people's wisdom, which lasts only a thousand years; Liu Hui is proficient in arithmetic, which has never been done before, and has created forward-looking theories such as number system and face body, which are strategic, unique and innovative. Others, such as seeking the number of emblems, the square cover of the Mouhe, the new method of equations, the method of weight difference, etc., all stand at the pinnacle of human wisdom and overlook all living beings. Such a person, compared with the emperor and Confucius and Mencius, may be inferior to the current or hundreds of generations, but in the future and even for thousands of generations, he is the real teacher who can be called a sage! ”

Zu Huo Ran stood up, walked quickly to Xu You, his eyes were shining, and said, "What's your name?" ”

It turned out that Xiao Yushu's introduction, he didn't hear it at all, Xu You said respectfully: "Boy Xu You, meet Mr!" ”

Zu Hao stretched out his hand to hold his arm and said, "Please get up!" Then he let him into the house and said, "Come in and speak!" ”

Xu You just wanted to take a step, but he noticed that something was wrong, looked at Xiao Yushu, and said, "General first, please!" ”

Xiao Yushu smiled and waved his hand, and said, "You guys talk first, I still have military affairs." Weizhi, you promised me, seven days later, I will hear the good news! ”

"Good!"

"No jokes in the army?"

Xu You was willing to fall for him, and said: "I am not a general's department, nor am I a court sergeant, and the general's military law has nothing to do with me!" However, with Mr. Zu here, I am at least ninety percent sure that I can let the general get what he wants! ”

"That'...... I'm waiting for good news! ”

Waiting for Xiao Yushu to leave, Zu Yu pulled Xu You into the house, but the house was full of calculations, and there was nowhere to put his feet, but he was informal, his feet were indiscriminate, he kicked the chips into the corner, and took out two rotten shapeless futons, and knelt down with Xu You in front of him.

"How did you know how to calculate at such a young age?"

"I have a lot of books at home, and I think it's interesting, so I often ask for advice, so I know a little bit about it, and I don't dare to say that I know everything!"

On a whim, Zu Xiao intended to test Xu You's level, and said, "I'll test you?" ”

Knowing that if you don't completely convince this person today, if you want to do something serious, I'm afraid it will take a lot of trouble, Xu You said: "Please ask Mr. to ask the question!" ”

"Nine times three-fifteenths, how much do you ask?"

"Two ninety-four or five!"

"Huh?" This is the third time that Zu Xiao let out a sigh today, and said, "Don't you have to make calculations? ”

Xu You smiled and shook his head.

Zu Xiao didn't go to his heart, after all, practice makes perfect, this question is relatively simple, and the answer can also be obtained by mental arithmetic. However, it can be seen from this that Xu You is not bragging, and he does have a lot of research in arithmetic.

"I'll give you another question: today there is a pound of raw silk that is folded into five taels, and a pound of silk dyed is three taels; Today, there are fifty-six pounds of raw silk, eight two or seven two-fourths, ask the geometry of dyed silk. ”

This is a little complicated, Xu You picked up a short wooden stick casually, and came up with an answer in an instant, saying: "Forty-six catties, two hundred and twenty-two, four hundred and forty-eight, two hundred and twenty-three." ”

Zu Xiao didn't intend to stump Xu You with this question, but when he saw his method of solving the problem, he was a little dumbfounded, and exclaimed: "What kind of word are you, what algorithm?" ”

Arabic numerals combined with vertical arithmetic are one of the greatest innovations in mathematics, and it is no wonder that even a great mathematician like Zu Hu was completely shocked when he saw it for the first time.

"This is the word of the scriptures, as for the algorithm, I call it jade calculation! Taken together, it is called the Heavenly Scripture Jade Calculation! ”

"Heavenly Scripture Jade Calculation...... Heavenly Classics and Jade Calculations ......" Zu Yu was keenly aware of the revolutionary innovation of this algorithm, and looked at Xu You with blazing eyes, but he stopped talking, and his expression was full of embarrassment.

Xu You didn't know at all, and said with a smile: "Sir, do you still have a topic?" ”

Zu Xiao understands that since ancient times, Xu You is not willing to tell the secret of the Heavenly Classics and Jade Calculations so easily, and he has the idea of competing at the moment, with his intelligence, he may not be able to compare with the other party.

"Okay, I'll ask you another question: there is one chicken today, which is worth five; The hen is one, and it is worth three; Three chicks are worth one. Where you buy 100 chickens for 100 dollars, ask the chickens and hens. ”

"Huh?"

This time it was Xu You's turn to sigh lightly, isn't this the extremely famous problem of 100 chickens in ancient times? In another time and space, the person who proposed this indefinite equation problem was called Zhang Qiujian, who wrote a very famous book called "Zhang Qiujian's Calculation Sutra", calculating time, and this person happened to live in the period of the Northern and Southern Dynasties.

Or in this chaotic world, there are also people who have found the existence and solution of indefinite equations. Xu You's brows furrowed slightly, and he quickly listed the equation with a short wooden stick, and then gave the answer: "Chicken Weng four, chicken hen eighteen, chicken chick seventy-eight; Eight chickens, eleven hens, eighty-one chicks; Twelve chickens, four hens, and eighty-four chicks. There are three answers, sir, I don't know if I'm right? ”

Zu Xiao was not only dumbfounded this time, but stared at the equations listed by Xu You for a long time. Xu You didn't say anything, silently waiting for him to recover from the shock.

For a long time, for a long time,

Zu Xiao pointed to X, Y, and Z on the ground, and asked in a hoarse voice, "Is this also the word of the Heavenly Scripture you said?" ”

"Yes, there are many ways to write the Tianjing characters, all of which are born for arithmetic, and they are extremely convenient to use. If you are interested, I will tell you all about it in the future, and I will not hide it! ”

"Really? What's so embarrassing...... Zu Xiao raised his head suddenly, his lips squirmed for a while, and he turned his head away. He is not good at words, and he is not good at meeting horses, he originally wanted to be close to Xu Youtao, but when the words came to his mouth, he couldn't say anything anyway.

Xu You felt that Zu Yu was very cute, the more simple and simple people who had no distractions in their hearts, they could go further and further on the road of science, and suddenly said: "I asked Mr. just now, but is the circumference rate of the circumference used to cut the circle?" ”

"Huh?" Zu Xiao almost regarded Xu You as a ghost, and said, "The question of a hundred chickens is an indefinite equation that I studied only a month ago, and you can answer it in an instant." That's it, you can use the circumcision technique to find the rate, how do you see it? ”

Xu You smiled: "Sir's heart is upset! At the beginning, Liu Hui created the circumcision technique, in order to find the invariant number of the circumference and the diameter of the circle, which is the so-called 'rate', and was familiar with the "Nine Chapters of the Commentary", and saw that it was not difficult for Mr. to ask! ”

"No, it's no wonder that you know how to circumcision. But this 'rate' is a word that haunts my mind from time to time, and I intend to use it as an expression of the divisor of the week and radius, and I have not yet confided in anyone......"

Xu You looked up to the sky and snorted, he really didn't know that the original use of the word "rate" as a ratio started with Zu Chongzhi. In the state of Chu, there was naturally Zu Yu who replaced the role of Zu Chongzhi, and the words that should have been invented and created by the lieutenant colonel were invented by the lieutenant colonel, but he was allowed to act on his behalf.

That's embarrassing!

"The so-called heroes see the same thing, you and I both think that the word "rate" is appropriate, then let's settle it, and in the future, this circumferential divisor will be called "ancestral rate"! ”

"This must not be ......"

Xu You didn't care, and said, "Sir, this is all a small section, you don't have to shirk, this is also what you deserve." Liu Hui used the circumcision technique to exhaustively study the reason, and found that the 'rate' was between three zhang one foot four inches and one minute and five centimeters and three zhang one foot four inches and six centimeters, which was roughly correct, and it was much stricter than the diameter in the Zhou Ji Sutra. I don't know where Mr. has calculated at the moment? ”

Zu Xiao said dejectedly: "I have exhausted several years, day and night, and I have only calculated the 'milli' backwards, three feet, four inches, one minute, five centimeters, and nine millimeters!" ”

Since Liu Hui, in the process of calculating pi, he has used eight units, such as zhang, ruler, inch, minute, centimeter, millimeter, second, and sudden, and the smaller units below the flicker are no longer named, but collectively referred to as micro.

Xu You praised: "Liu Hui's circumcision technique has been pushed to three feet, one foot and four inches, in fact, it has reached the limit of manpower, it seems to be a millimeter back, but it has to be calculated endlessly, Mr. can persevere, You really admire!" ”

Circumcision is actually to find the area of the regular polygon in the circle, from the four sides, six sides, eight sides to the ninety-six sides, Liu Hui got the value of 3.14, and then cut to the positive 192 side, it can no longer be cut, so it is very clever to use a few floating approximations, using the weighted average algorithm, pushed to 3.1416, which is equivalent to the value that can only be obtained by the positive 3072 sides.

And when Zu Chongzhi finally pushed it to 3.1415926, it was equivalent to the value of 24576 side hours, and in the era when there was no computer, it was a miracle to deduce such a value just by fiddling with clumsy calculations.

The German historian of mathematics Cantor said: "The accuracy of pi calculated by a country in history can be used as an indicator of the level of mathematical development of that country at that time." ”

Zu Chongzhi's pi is more than 1,000 years ahead of the world.

Ancient China not only had the most advanced culture, but also the most advanced science, but it gradually declined, which is a pity. Xu You came to this world again, revenge is only the most insignificant thing, what he wants to do, or what he wants to accomplish, is far deeper and broader than the hatred of a surname and the fortune of a country, and even surpasses the boundaries of the dispute between Hu and Han.

Culture and science and technology, no matter what era it is, will always be the most important, the most core and the most competitive thing of a nation!