Luo Yong's idea is that he actually wants to lay a foundation first.

After all, the subject of mathematics plays an important role in the development of many modern sciences in the future. Now we start laying the foundation early, and we will inevitably benefit in the future.

Of course, it is not only Arabic mathematics that is called mathematics. Traditional Chinese mathematics is also mathematics. What Luo Yong currently teaches can only be regarded as some basic arithmetic. This is only the most basic and simplest part of the entire mathematical knowledge system.

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

Later studies have shown that these Arabic numerals originally originated in India. Around the 8th and 9th century, the Arabs created a "Palace of Wisdom" and gathered scholars from all over the world to translate and collect many classics from the world at that time.

From the initial period of translation-oriented introduction to the widespread use of Arabic and continuous development, it finally became a numerical symbol that was common internationally. This is the general development process of Arabic mathematics.

At this time in the early Tang Dynasty, the "Dashi" people mentioned by the Tang people refer to the Arabs.

It is now 635 AD. Five years ago, that is, 630 AD. This year was the "year of delegation" of the religion. Mohamed led his believers to conquer Mecca. Other tribes on the Arabian Peninsula came to worship and converted to the leadership of Mohamed. The Arabian Peninsula achieved unity and continued to expand outward to form the Arab Empire.

Luo spent a lot of time before summarizing such information from the pile of books and miscellaneous materials in his space.

Luo Yong's mood is also a bit 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 635 AD, just over a decade after the founding of the Tang Dynasty, and the Arab Empire was emerging. What was the situation in other parts of the world? What was the situation at this time? What about Europe?

Just before Tang Jian arrived, Luo Yong was still thinking about such a question in his mind.

It was another snowy day this day, with heavy snow falling down, and sometimes a cold wind blew by, blowing snowflakes in the sky flying all over the sky.

Tang Jian sat on the tall horse, watching Luo Yong lead his disciples and strode towards him.

The young man had a thin figure, a tender face, and a clear and firm eyes. When he stood not far ahead and looked at them, Tang Jian felt that his eyes seemed to be able to travel through this thick snow curtain, across the mountains and ridges, through the unknowns and chaos.

How could such a person be a thing in the pool? Tang Jian guessed that the saint should be a little wary of Luo Sanlang. This time he heard that he would strengthen the military defense in the Mengmen Pass area.

Is this the person who is defending this? Was the Hu people outside the pass or Luo Sanlang inside the pass?

As his thoughts turned around, the two sides were close, but Tang Jian didn't show anything. He turned over and dismounted, smiled and greeted Luo Sanlang and others who were walking towards him. After some greetings, he first sent the copper coins and silk cloth to the Luo family yard, and then the group still went to the Xu family's guest house for dinner.

His Majesty the Emperor was anxious to get the prescription of Eucommia Gluten and Earth Cement, so Tang Jian naturally did not dare to neglect it. That night, he had a detailed discussion 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 naturally had to give them.

What can't be given? He did these things in advance, not to exchange them for great benefits. It would be fine if he could get some copper coins and silk cloth.

"I heard that the war is in the southwest, and it is time for the shortage of money and food. Just for these two earthly recipes, how can you make your Majesty spend so much money?" Luo Yong refused.

"If Sanlang uses these two parties to make profits, his income will be more than just 500 trump cards. Your Majesty is also grateful to Sanlang Gaoyi. Although the national treasury is tight, he will not treat Sanlang too badly." These scenes are naturally very nice to say.

It is a fact that the national treasury is tight, but it is not enough to fall into a dilemma for a thousand or eight hundred trump cards. Today's saints have always been meticulous. Whether it is the management of the official team or the income and expenditure of money and grain, they are always very careful.

The Tang Dynasty now has only a population of this population, and the taxes collected every year are limited. It also needs to live in people's livelihood and develop the economy. There are often wars on the border. It is definitely not possible to use some flowers without meticulously. Even if you are an emperor, you cannot spend as much as you want.

Luo Yong naturally knew that the emperor refused to offer him a high price, which was normal. His current situation was like a child who took a rare treasure to pawn the pawn shop. It would be strange if someone could offer him a high price. It would be considered very kind not to just ignorant of the things. If he met someone who was so mean, he would probably even lose his life.

Since Li Shimin was the emperor, he had never seen any scenes. Luo Yong was not close to him or her, and he was in the right way to benefit him. Can he still expect him to give in to him? It would be very good to be able to give these things.

Afterwards, Tang Jian and others rested in Xipo Village for two days. It was really difficult to walk in winter. Finally, they walked all the way from Chang'an City to get here for a short rest for two days. I think the saints would not blame him.

Tang Jian has not been idle these two days. He ran to Luo's yard early in the morning every day, and pestered Luo Yong to teach him the vertical calculation method all day long.

This man was good at the beginning and studied hard. Looking at his enthusiasm, he seemed 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 desire for knowledge.

"This method is really useful. 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 very short time, Tang Jian couldn't help but sigh.

In the past, when people did arithmetic, they mainly rely on their brain power. Most of them are not smart enough to adjust and adjust clearly enough. Most of them are not very good at counting. Small numbers are OK, but when they encounter large numbers, they are completely unsatisfied. With this vertical arithmetic method, you don’t have to worry about how big the number comes.

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

"I've heard Hu Shang say a few words." Luo Yong said.

"It's true!" Tang Jian said excitedly! Knowing that this kid was throwing bait, he had to bite the hook, and he was willing to bite it.

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

"Tell me, what do you want me to do?" Tang Jian is so smart. What else can I not understand? I just want to negotiate terms with him.

"It's not a big deal." Luo Yong smiled and said, "I heard that in the several academic museums in Chang'an City, students from four schools can make up for the Taixue? How is this a supplementary method?"

"Do you want to send your brother to Chang'an City to study?" Tang Jian probably also realized that Luo Sanlang was not interested in studying now, and he might not want to go to Chang'an City. At this moment, he asked him about this matter, and it was probably because of his younger brother.

"Goro is still young now, so let's talk about it in a few years." Luo Yong said: "I have a classmate, and now I am studying in the Four Schools."

"Do you want me to help him with the Taixue?" Tang Jian carefully measured the boy in front of him. After all, he was still a child. Look, how innocent and cute this is said. Please help me transfer a classmate to a school.

"After all, it's a classmate." Luo Yong naturally wouldn't talk much about his own little thoughts. Even the person involved, he might not have a day to let the other party know. How spacious and easy to walk on the straight road, why bother dragging people to the single-plank bridge?

"..." Tang Jian pondered. He could still make this place in the Imperial Academy. This behavior was naturally to prevent Luo Yong from thinking that this matter was easy.

"..." Luo Yong didn't say anything. You can do it yourself. Anyway, it doesn't matter. Luo Yong will definitely not teach the vertical calculation method of multiplication and division. Of course, if they explored it themselves, they should be able to figure it out. After all, there are addition and subtraction, which just takes a lot of effort.

Then whatever the emperor said was what he said. Luo Yong had no room for bargaining. Just forget about it, but we should do whatever we should do.

Sure enough, after some thought, Tang Jian finally let go: "I'm afraid this year won't work. I'll help him see it in the spring of the next year."

"So, thank you Mr. Tang." Luo Yong smiled and bowed to the other party. The Imperial Academy restricted the quota of students, and there were many people in Chang'an City staring at this matter. It was really too anxious to do this matter. He had to wait for the opportunity. Tang Jian had already agreed, and he would have to do it sooner or later.

The transaction was established, and Luo Yong taught the other party the multiplication and division of the vertical calculation method according to the words. Tang Jian would have been multiplication by the nine-nine multiplication formula, and the arithmetic was also good. At this time, he had already remembered the Arabic numerals from 0 to 9. Luo Yong just arranged a few vertical patterns to show him, and the other party quickly understood what was going on.

Now! That was really a treasure, especially when it comes to the calculation of division, he couldn't let go. He squatted there alone, obeying a small blackboard and then calculating. No matter how he calculated, he was not tired of it.

It’s a pity that the time was too short, so they were about to rush back to Chang'an City. Before leaving, Luo Yong gave each of them a small gift, a threaded blackboard that could be hung on his waist, was a little bigger than an ordinary waist tag.

These small blackboards are not all black, and they also have cyan ochre colors. They are dyed first, and then applied tung oil on them. The front can be written in plaster, and the back is a 99 multiplication table, written in Arabic numerals, and then drawn on the table, which is exactly the same as the 99 multiplication table on the back of the pencil case when Luo Yong was a child.

The next morning, the group of people hung colorful boards on their waists, and set off from Xipo Village with risks all over the sky.

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.

This time, the two prescriptions given to the emperor, the cement prescription, actually have many things that can be improved. I wonder if the craftsmen from Chang'an City can improve the formula of earth cement to create more solid and durable ordinary cement or even some high-strength special cement.

If they improve, there will naturally be no use of Luo. If they do not improve, Luo will still have some information that can be used here.

There are also those rubber-soled leather boots. Although ordinary people can't afford to wear them with their current output, they will eventually become different as time goes by.

In the early days, when Ma Yi first appeared, not everyone could afford it. At this moment, although the lives of ordinary people are still difficult, they can at least wear linen clothes.

The same is true for the sole of Eucommia ulmoides. As more and more people plant Eucommia ulmoides, I believe that this sole will gradually become popular in a long time. Although the process of making glue is cumbersome, it is nothing compared to the process of planting linen weaving cloth.

Luo Yong returned to his yard, entered his house, walked to a pottery jar by the wall, lifted a random grate on it, and then opened a layer of fine sand at the mouth of the jar, and saw the dark brown seeds below.

The planting of Duzhong trees was not originally mainly for leaves, and the bark contained the most glue. Later generations used seeds to sow seeds during production. After two or three years, the entire sapling was cut down, peeled and taken to obtain Eucommia gel.

Among the seedlings that Luo Yong bought in spring, some of them are older and have already produced some seeds sporadically this year. When the leaves are harvested in autumn, Luo Yong carefully collects these seeds, and when the spring comes to the coming year, they can be used to sow them.
Chapter completed!