"Okay, since His Highness is so sure, then the poor road is arrogance!" Li Chunfeng agreed without thinking about it, firstly, he didn't believe that Li Yu could have any way to simplify, and secondly, even if he lost, he would not suffer, but knew a way to simplify arithmetic. As for the two arithmetic and heavenly problems in Li Su's mouth, he didn't pay attention to it.

Li Su and Li Chunfeng's bet attracted Yuan Tiangang and Yifan, but Zhao Fu didn't have the slightest interest in these arithmetic, but it was about Li Su, who was the top boss, and he could only accompany him with his spirit.

"Okay, happy!" As soon as Li Su saw the other party's plan, he immediately yelled happily, then took the pen and paper on the bookcase, and explained while writing: "If you want to simplify the current algorithm, the first step is to simplify the numbers, in the past, you all used to use Chinese characters to calculate the twenty-sixth chapter of Chang'an's primordial meridian, and now we use a new set of number symbols to replace Chinese characters......"

Li Su used miserable calligraphy to write out all the Chinese characters from one to ten, wrote the corresponding Arabic numerals below, and wrote the operation symbols such as addition, subtraction, multiplication, and division, and then explained them to Li Chunfeng one by one. These things are actually a layer of window paper, plus the three of them are all extremely smart, so they can understand it as soon as they hear it.

Then Li Su took the binary one-dimensional equation made by Yifan just now as an example, substituted two unknown numbers x and y, listed the two equations, and obtained one of the values after eliminating the yuan, and the second value naturally came out. All of them were checked together, but it was only three or four lines, and the whole time added up to less than a minute, which was like a miracle for Li Chunfeng and them.

"This ...... This...... It's just incredible! Li Chunfeng and Yuan Tiangang were still in shock. Yifan was the first to say in surprise, and then he didn't care about other people, he took a piece of paper, and tried to check other topics according to the method that Li Su just said, at first it was a little jerky, but with Li Su's guidance. Soon became proficient, and after a while, it turned out that all the topics on the paper were made in Chapter 26 Chang'an Prime Meridian.

At this time, Li Chunfeng and Yuan Tiangang finally came to their senses. Seeing Yifan's actions, he couldn't help but feel a little itchy, and tried the calculation of these number symbols himself. As a result, I have a deeper understanding of these simple and convenient calculation methods. For a while, the gaze that looked at Li Su also changed a little.

"Your Highness, Chunfeng has lost!" Li Chunfeng bowed to the ground, even his self-proclaimed name changed, and his face showed a bit of sincere admiration, wanting people like them to really admire, unless they could overwhelm the other party in learning, and Li Chun did just that.

"Hehe, Daoist Li doesn't have to be polite, I just know these tricks. When it comes to attainments in arithmetic, let alone being a Taoist, it is estimated that even if it is Yifan, it is much stronger than me. "What Li Su said was the truth, at least he wouldn't calculate the movement of any celestial bodies.

"Your Highness is too modest!" Yuan Tiangang stroked his beard and smiled. In the past, I just heard others say how Li Su was, but when I saw it today, it was really worthy of his reputation, and it was really surprising that he had such attainments in arithmetic.

"Your Highness, Chunfeng admits defeat in the bet. It's just that I don't know what the two problems in your mouth are, if even His Highness can't solve them, then Chunfeng may not be able to help. Li Chunfeng said with a look of shame, he only thought that he was unparalleled in learning, but today he knows what it means to be a person outside the world.

"Haha, Brother Chunfeng, it would be too much to call His Highness, in the future, you and Daochang Yuan will call me Liulang, anyway, people close to me will call me that." Li Chunfeng was not in a hurry to say the two questions, because these two questions could not be solved in a day or two, and Li Chunfeng would be busy in the future.

"Yes, yes! I also think it's troublesome to call your Highness every day, but Rokuro is still good. Yuan Tiangang and Li Chunfeng haven't expressed their position yet, but Yifan said happily that she and Li Su have a very good talk, and they are very arrogant, and they have never regarded Li Su as the king of Qi in their hearts, but they usually call Li Su His Royal Highness in front of others, otherwise her father Zhao Fu will be very unhappy. Yuan Tiangang and Li Chunfeng are both outsiders, and they don't care about what they are called, plus Yifan agreed, so they nodded yes.

"Okay, then let's talk about these two problems, in fact, the first one is okay, it's not very complicated, the second one is very closely related to the first, but it's a little troublesome to solve."

Hearing that Li Fu finally began to talk about the two mysterious problems, Li Chunfeng and the three of them immediately listened attentively, while Zhao Fu next to him had a drowsy expression, after all, in the eyes of a layman, these things were simply too boring.

Looking at the serious performance of the three of them, Li Su sorted out his thoughts for a while, and then said: "I think everyone knows that the land we live in, including the surrounding ocean, is all on a sphere!" After hearing this, the three of them nodded violently, a question that even an amateur astronomy enthusiast like Li Shimin knew, let alone the three experts in front of him.

"Well, since it's a sphere, it brings us a problem of positioning, if it's on land, there are mountains and rivers to refer to, but if it's on the endless sea, how should we know where we are?" Li Su asked step by step.

"This ......" Hearing Li Su's question, Li Chunfeng and Yuan Tiangang were silent for a while, they used to live on land for most of their time, rarely went to sea, and never thought about this problem.

Li Su waited for a while, although the three people in front of him were all brilliant people, but they couldn't think of any good way for a while, so he said again: "If you want to solve this problem, then you must introduce the concept of longitude and latitude, the so-called horizontal line is the latitude, and the vertical line is the longitude......

Li Su slowly explained the knowledge he knew about the warp and weft, although it was only a foundation, and there were even some deficiencies and mistakes in some places, but for Li Chunfeng and the three of them, it was tantamount to opening a new door, not only quickly understood the meaning of warp and weft, but even on the basis of Li Su's explanation, he thought of some other knowledge in warp and weft.

"Your Highness is really able to do what ordinary people can't, and the poor Dao is impressed!" After listening to Li Su's speech, Yuan Tiangang was the first to stand up and salute, and Li Chunfeng followed closely behind, although Yifan did not salute Li Su, but he winked at him mischievously, which was a compliment to Li Su's erudition.

"Hehe, this is just the kid's cranky thoughts when he is usually fine, there must be many fallacies, but it makes the Taoist laugh." Li Su's face has been cultivated to King Kong is not bad, and there is no change in his face after plagiarism.

"Your Highness is talking about this concept of warp and weft, so you want me to help Your Highness complete this knowledge?" Li Chunfeng's eyes lit up, and he asked eagerly.

"Haha, Brother Chunfeng is really powerful, and he guessed the key at once." Li Su said with a smile, professional knowledge is still handed over to professional talents, as long as he makes a start and points in a direction, someone will naturally help to supplement, after all, Datang is so big, are you afraid of the lack of available talents?

"Your Highness, rest assured, as long as Chunfeng is given a period of time, he will definitely sort out all the relevant knowledge." Receiving Li Su's affirmative answer, Li Chunfeng immediately became excited, although Jingwei is just a concept, but its meaning is extremely unusual, if nothing else, it is definitely a beautiful thing that can be famous for eternity. Although Li Chunfeng is not greedy for money, he attaches great importance to the word 'name', otherwise he would not be an official.

"Brother Chunfeng, it's not enough to sort it out, I also want to build an observatory in Chang'an, just outside Chang'an City, on the extension of Suzaku Street, and then name the meridian through Suzaku Street and the observatory as the prime meridian, that is, the zero degree meridian, and all the meridians on the earth start from this! And this matter, after you return to Chang'an, you will personally supervise the construction, and as for the funds, it will be paid by my Qi Palace. ”

Li Su said ambitiously that the prime meridian of his previous life was located in the United Kingdom, which was a testimony to the glory days of the British Empire. Now Li Su wants to set the meridian on the Vermilion Bird Street in the Tang Dynasty, and this street happens to run north-south, which can be regarded as having its own destiny in the dark, and as long as it is there, no one will forget the glory of the Tang Dynasty.

"Great idea!" Li Chunfeng and Yuan Tiangang clapped their hands together and praised loudly, while Li Chunfeng thought about it, and suddenly smiled again, "Your Highness, in fact, you don't need to contribute at all, if I entrust this matter to Your Majesty, with Your Majesty's temper, I should be very happy to allocate funds to build this observatory." ”

When Li Su heard Li Chunfeng's words, the two looked at each other with a tacit understanding, and then laughed. Indeed, with Li Shimin's temper of great joy, is it strange that he doesn't rush to do this kind of thing that can leave a name for himself in future generations?

"The concept of latitude and longitude is really good, but there is also a very important question, that is, how do we know the latitude and longitude we are in?" At this moment, the clever Yifan suddenly asked a difficult question.

"Yes, just like Liulang, you just said, it's okay on land, there are references to mountains, rivers and rivers, but if it's on the vast sea, then these references are gone, unless ......" Yuan Tiangang heard Yifan's question, and agreed at first, but as his thinking progressed, he suddenly thought of a solution, and his eyes immediately showed a trace of ecstasy.

"Haha~, unless you use the sun, moon and stars as a reference." Li Chunfeng took the master's words, and then said, with their ingenuity, as long as Li Su raised his head, he could immediately let them come up with a follow-up solution.

"But if you take the sun, moon and stars as a reference, if you want to determine the latitude and longitude you are in, you must be proficient in astronomy and arithmetic, I don't have many people in Datang, if you want to match one on every sea ship, it is really unrealistic." After being reminded by the master and the senior brother, Yifan also came to his senses and thought of a way to determine the direction through calculation, but then he thought of a very practical difficulty.

Listening to their discussion, Li Su was extremely surprised in his heart, these three people are really rare talents in Datang, and he hasn't even had time to say the second question, they have already thought of it. (To be continued)RQ!!