North and South groceries

Luo Yong's idea, he actually wanted to lay a foundation first.

After all, the subject of mathematics has played a very important role in the development of many modern sciences. Now that the foundation has been laid early, it will definitely benefit in the future.

Of course, not only Arabic mathematics is called mathematics, traditional Chinese mathematics is also mathematics, and what Luo Yong is currently teaching can only be regarded as some basic arithmetic, which is only the most basic and simplest part of the entire mathematical knowledge system.

The so-called Arabic mathematics is the mathematics studied in Arabic. The researchers here are not only Arabs, but also people from many other countries and regions.

Studies in later generations have shown that these Arabic numerals originally originated in India. Around the eighth and ninth centuries, the Arabs built a "Palace of Wisdom" and gathered scholars from all over the world to translate and collect many classics in the world at that time. .

From the initial period of introduction mainly through translation, to the widespread use of Arabic, continuous development, and finally becoming a universal number symbol in the world, this is the general development process of Arabic mathematics.

At this time in the early Tang Dynasty, the "big food" people in the Tang population referred to the Arabs.

It is now AD 635. Five years ago, that is, AD 630, this year was the "year of delegation" of Islam. Muhammad led his followers Muslims to conquer Mecca, and other tribes on the Arabian Peninsula came one after another. After worshiping and converting to the leadership of Muhammad, the Arabian Peninsula was unified and continued to expand outward to form the Arab Empire.

It took Luo Yong a lot of time to gather such information from the pile of books and miscellaneous materials in his space.

For Muslims, Luo Yong's mood is somewhat complicated, but no one can deny that Arabic mathematics developed under the bearing of Arabic is an irreplaceable treasure in the history of human civilization.

It is now AD 635, just over ten years after the founding of the Tang Dynasty, and the Arab Empire is rising. What is the situation in other parts of the world at this time, what about Europe?

Just before Tang Jian's arrival, Luo Yong was still thinking about such a question.

This day was another snowy day, with heavy snow falling on the ground one after another, and sometimes a gust of cold wind blows through, blowing the snowflakes flying all over the sky.

Sitting on the big horse, Tang Jian watched as Luo Yong led his group of disciples striding over here.

The young man was thin, with an immature face, and his eyes were clear and firm. When he stood still not far in front and looked towards them, Tang Jian felt that his gaze seemed to be able to pass through the thick snow curtain. Through the mountains, through the unknown and chaos.

How can such a person be a thing in the pool? Tang Jian guessed that the saint should be a little wary of Luo Sanlang, and this time he heard that the military defense in the Mengmen Pass area will be strengthened.

Are they guarding against the barbarians outside the pass, or Luo Sanlang inside the pass?

In the blink of an eye, the two sides were already close, but Tang Jian didn't show anything on his face. He got off his horse, smiled and greeted Luo Sanlang and others who were coming towards him. The copper coins and silk cloth were sent to the courtyard of Luo's family, and the group of people still went to Xu's guest house for dinner.

His Majesty the Emperor was anxious to get the prescriptions for eucommia glue and earth cement, so Tang Jian naturally did not dare to neglect. That night, he had a detailed talk with Luo Yong in the Luo family hall.

Luo Yong was not surprised that the emperor would want these two prescriptions. Since he wanted them, he would naturally have to give them.

There's nothing he can't give, he didn't do these things in order to get much benefit for himself, he just got some coins and silk cloth.

"I heard that there is a war in the southwest, and it is the time when money and food are in short supply. How can His Majesty spend so much money just for these two recipes?" Luo Yong declined.

"If Sanlang seeks profit from these two ways, he will earn more than just five hundred guan. Your Majesty is also grateful for Sanlang's high righteousness. Although the national treasury is tight, he is not willing to treat Sanlang too badly." These scenes are naturally how to say it nicely.

It is true that the national treasury is tight, but it is not enough to get into a predicament for the sake of thousands of dollars. Today's saints have always been meticulous. Whether it is the management of the official team or the income and expenditure of money and food, he is very close.

The current Tang Dynasty has only such a small population, and the taxes collected every year are also limited. It is also necessary to live with the people and develop the economy. There are often wars on the border. As an emperor, you can't spend whatever you want.

Naturally, Luo Yong also knew that it was the emperor who refused to pay him a high price, which was normal. His current situation was like a child taking a rare treasure to a pawnshop to pawn. , It is already very kind not to confuse things directly, if you encounter a dark heart, I am afraid that even your life will be broken in it.

Since Li Shimin is the emperor, he has never seen any scenes, and Luo Yong is not related to him, and his interests are at hand, can he still be expected to give way to him?It would be great to be able to give these.

Afterwards, Tang Jian and others rested in Xipo Village for two more days. The journey in winter was really difficult, and they finally walked all the way from Chang'an City to this place. If they had a short rest for two days, they would not blame the saints.

Tang Jian has not been idle for the past two days. He ran to Luo's yard early in the morning every day, pestering Luo Yong to teach him the vertical calculation method.

This person has a good background, and he is serious about his studies. Seeing his enthusiasm, he seems to want to take out all the knowledge in Luo Yong's belly and study it one by one.In less than two days, vertical addition and subtraction could no longer satisfy his thirst for knowledge.

"This method is really easy to use. Even if you are not very smart, you can do arithmetic as long as you learn this method." After mastering vertical addition and subtraction in a short period of time, Tang Jian couldn't help expressing such emotion.

In the past, when people did arithmetic, they mainly relied on brain power. If the brain is not smart enough to adjust and not clear enough, most of them can’t do it. Formula arithmetic method, no matter how big the number comes, don't be afraid.

"It's a pity that there are only addition and subtraction methods. It would be great if there are multiplication and division methods." After sighing, I felt a little regretful.

"I heard a few words from that Hu businessman." Luo Yong said.

"It's true!" Tang Jian said excitedly!Knowing that this kid was throwing bait, he had no choice but to bite the hook, and he bit it willingly.

"..." Luo Sanlang smiled without saying a word.

"Tell me, what do you want me to do?" Tang Jian is such a smart person, there is nothing he can't figure out, just want to negotiate terms with him.

"It's not a big deal." Luo Yong said with a smile: "I heard that in those academies in Chang'an City, students of the four disciplines can make up for the Taixue? What kind of way is this?"

"Do you want to send your brother to study in Chang'an City?" Tang Jian probably also saw that Luo Sanlang has no intention of studying now, and he may not really want to go to Chang'an City. Asking him about this right now must be for him. that brother.

"Wu Lang is still young, let's talk about it in a few years." Luo Yong said, "I have a classmate who is now studying in Simen."

"Do you want me to help him make up for his imperial education?" Tang Jian carefully looked at the young man in front of him, he was still a child after all, look, how innocent and cute he said this, please help one of my classmates transfer to another school.

"After all, it's a classmate." Regarding his small thoughts, Luo Yong will naturally not talk to others. Even if he is the person involved, he may not let the other party know one day. The road of heterosexuality is so wide and easy to walk. Why bother dragging people to the single-plank bridge.

"..." Tang Jian mused, he could still get the place of the Imperial Academy, and this posturing was naturally to prevent Luo Yong from thinking that it was easy.

"..." Luo Yong didn't say anything, you can figure it out if you agree or not. Anyway, if you don't understand this matter, Luo Yong will definitely not teach you the vertical calculation method of multiplication and division. Of course, if they If you grope, you should be able to figure it out. After all, addition and subtraction are all there, but it just takes a lot of work.

The old emperor is what he says, and Luo Yong has no room for bargaining.

Sure enough, after pondering for a while, Tang Jian finally let go: "I'm afraid it won't work this year, so I'll help him take a look at it in the spring of next year."

"So, thank you Tang Gong." Luo Yong smiled and thanked the other party. The Taixue restricted the number of students, and there were many people in Chang'an City staring at it. This matter is indeed too urgent. We have to wait for the opportunity, anyway. This Tang Jian has already agreed, and this matter will have to be handled by him sooner or later.

The transaction was established, and Luo Yongyi taught the other party the multiplication and division of the vertical calculation method. Tang Jian would have been taught the formula of ninety-nine multiplication, and his arithmetic is also good. At this time, he has memorized the Arabic numerals from 0 to 9 , Luo Yong just arranged a few vertical forms for him to see, and the other party quickly understood what was going on.

Now!That is really a treasure, especially for the calculation of division, I can't put it down, squatting there by myself, counting and counting in front of a small blackboard, he can't get tired of counting.

It's a pity that the time is too short, and they will rush back to Chang'an City soon. Before leaving, Luo Yong gave each of them a small gift, a small blackboard with thread, which can be hung on the waist, which is more unusual. The belt is bigger.

These small blackboards are not all black, there are also blue ocher ones, the wooden boards are dyed first, and then tung oil is applied on them. Writing numbers and drawing tables are exactly the same as the nine-to-nine multiplication table on the back of the pencil case when Luo Yong was a child.

Early the next morning, the group set off from Xipo Village, wearing colorful boards around their waists, and braved the risks.

Luo Yong sent Tang Jian and his party to the sheep pen. After saying goodbye, he watched them leave, and then rode five pairs back to his yard slowly.

In the two recipes given to the emperor this time, the cement recipe actually has a lot of room for improvement. I don’t know if the craftsmen in Chang’an City can improve the formula of earth cement to make a more durable one. Ordinary cement and even some high-strength specialty cements.

If they improved, naturally there would be nothing for Luo Yong. If there was no improvement, Luo Yong still had some materials that could be used.

And the rubber-soled leather boots, although with the current output, ordinary people would definitely not be able to wear them, but with the development of time, they will eventually become different in the future.

In earlier times, when sackcloth first appeared, not everyone could afford it.At this time, although the lives of ordinary people are still difficult, they can wear linen clothes anyway.

The same is true for Eucommia rubber soles. With more and more people planting Eucommia trees to make Eucommia gum, I believe that this kind of sole will gradually become popular in the near future. Compared with the process of cloth, it is nothing.

Luo Yong went back to his courtyard, entered his room, walked to a pottery urn by the wall, lifted a grate randomly placed on it, and then pushed aside a layer of fine sand at the mouth of the urn, and saw the pottery urn below. Layers of dark brown seeds.

The planting of du species of trees is not based on the leaves, but the bark that contains the most glue. In the production of later generations, seeds are often used for sowing. After planting for two or three years, the whole saplings are cut down. Peel the leaves and make Eucommia gum.

Among the saplings that Luo Yong bought in the beginning of spring, some of them are older trees, and some seeds have been sporadically produced this year. When harvesting leaves in autumn, Luo Yong carefully collected these seeds, and can use them when the next spring begins. sowing.

I believe that within a few years, the saplings of the Du species on the slope will begin to bear seeds on a large scale. At that time, Luo Yong can't use it all up, so he will naturally sell it for money.