Empress Changsun did not let Changle say this, obviously it was not really not letting her say it, it was just to alleviate Li Shimin's embarrassment. If Li Shimin still needs her eight-year-old girl to teach these things, where would Li Shimin give face?

"Did Huo Gang teach you these things?" Li Shimin thought for a while and asked directly. He didn't care. There were no one else here, and the maids were all personal maids. They dared not say these words casually.

"Yes, these are the knowledge in the mathematics book he gave me. He said that mathematics is the basis of all things, and almost everything in the world can be calculated using mathematics. For example, how much grain is earned in the Tang Dynasty every year, how much taxes the Tang Dynasty has increased, how much population the Tang Dynasty has increased, and how much average population taxes the Tang Dynasty has increased, and how much average per capita income is. These can all indicate whether the Tang Dynasty's national strength is rising or declining." Changle spoke seriously.

Li Shimin was stunned for a moment. The data mentioned by Changle actually counted by the Ministry of Revenue every year, but the results of the Ministry of Revenue statistics are not so detailed.

"Tell me in detail." Li Shimin was very interested, because this was definitely necessary for the future development of the Tang Dynasty.

"Father, I will give you an example. If the annual tax revenue of the Tang Dynasty this year is 2 million guan, and the annual tax revenue of the Tang Dynasty is 2.2 million guan next year. If the annual grain revenue of the Tang Dynasty increases by 1 million guan next year, do you think the Tang Dynasty is getting better?" Changle asked immediately.

"Of course this is getting better." Li Shimin immediately spoke.

"No, Father, this is actually inaccurate." Changle immediately spoke.

"Why is it inaccurate?" Li Shimin asked back.

"It's very simple. You have to look at how much the population of the Tang Dynasty has increased. For example, the population of the Tang Dynasty this year is 30 million and the tax revenue is 2 million guan. However, the population of the Tang Dynasty increased to 33 million next year. However, the annual tax revenue of the Tang Dynasty next year is 2.2 million guan. In fact, if the per capita tax revenue of the Tang Dynasty is actually not increasing, which means that the national tax growth of the Tang Dynasty has stagnated, which is definitely not good news for the entire country, which means that there is a problem with the Tang Dynasty."

"The same is true for increasing grain income. For example, our population of Tang Dynasty this year is 30 million, with a total of 100 million mu of arable land, and a total income of 220 million stones of grain. If the population of Tang Dynasty increases to 33 million next year, the total income of arable land will increase to 200 million mu, but the total income of 300 million stones of grain is 300 million stones of grain, which means that although our Tang Dynasty's grain has increased, the average grain income per mu of land has decreased."

"At this time, the father needs to send someone to investigate what causes the average yield per mu to decrease, whether it is because of the climate, water sources, disasters, or whether someone is filling his bags, etc."

"If it is climate or other problems, then the father needs to consider disaster relief in advance, because there will be no problems with food for the time being, and then there may be significant changes in the subsequent climate."

"If the per capita arable land in a certain area is too small, which causes frequent famines and other disasters in this place, you can consider immigrating the population of this place." Changle explained seriously.

These are things she has learned hard, and this is no longer purely in the category of mathematics. Of course, it is also right to say that it is mathematics. In fact, this is already related to knowledge in statistics and other aspects.

In this era, although the Tang Dynasty also counted similar data, there were only overall data, and per capita data was impossible, because the Tang Dynasty did not have so many computing talents.

It is hard for you to imagine that the germination of mathematics in China is ahead of the world, but the development of mathematics lags behind the world. This depends on the writing recording method in ancient China.

As we all know, mathematics is a discipline that attaches great importance to the derivation process. In ancient China, a large number of bamboo slips were needed to record. Due to the way the bamboo slips were written, many mathematical formula derivation processes in ancient China were all saved, and the results were left in the end.

In this way, it will be difficult for future generations to be inspired by the derivation of their predecessors. Some mathematicians who are more powerful in later generations have doubts when using the formulas and results of their predecessors, and they also need to prove themselves, which wastes a lot of mathematician's energy.

This can be seen from the way classical Chinese is written.

In fact, the Nine Chapters of Arithmetic appeared around 100 AD, but you can believe that after Zu Chong, a mathematician of the Southern and Northern Dynasties, almost all mathematics in the Sui and Tang Dynasties was in a stagnant state.

Therefore, if a small factor affects the development process of each civilization, perhaps a small factor may affect many things. A bamboo slip record affects the development of mathematics. However, because there are few people in the West and more animal skin records, it can record pictures and texts in detail, study geometry, and then gradually record the process. Many mathematicians will gradually absorb the knowledge of their predecessors.

However, in fact, it is incorrect for us to use the thinking of later generations to deduce history. Such a priority theory is not correct, because the mathematics we learn has been professionally planned by countless mathematicians to formulate the process and timeline of mathematics learning for us. However, in fact, many simple mathematical laws may not be discovered in history, but some are rare.

In this era, knowledge is very rough, and no one knows what kind of knowledge can be invented first.

Therefore, the summary of later generations is very necessary.

The maths that Huo Gang came up with are actually a perfect mathematical system in later generations, so they are very important.

Just like what Changle said, as an emperor, Li Shimin never thought that a mathematical science would have such a great impact on the country. Although the Tang Dynasty actually stipulated that nine chapters of arithmetic were textbooks in the imperial examination.

However, some of the knowledge in Nine Chapters Arithmetic is difficult, and it is actually not suitable for popular learning.

The most important thing is that the knowledge of this system is the most important, especially in application scenarios, which are the key things.

Li Shimin only needs to think about these things carefully to know how useful it is. Just as Changle said, if all these data in a county are clear, then if these data fluctuate too much next year, you will immediately know that there must be some problems in the county.

However, it is not easy to count these data at all, because it means a large number of talents who know how to calculate.

Li Shimin suddenly thought of what Wei Zheng reported to him in detail before. More than a dozen departments of the Han Dynasty were actually not related to the political system of the Han Dynasty, but it can be seen from the names of these departments that what exactly do these departments do.

Among these departments of Dahan, there is an audit department called the Audit Department, which is probably doing these tasks. In this way, Dahan's control over his entire country far exceeds Li Shimin's understanding of the Tang Dynasty.

To be honest, if Changle hadn't told him, Li Shimin would not have imagined how much these data would have for the Tang Dynasty, but after Changle said this, he would have understood how much these data would have for the Tang Dynasty.

Just like the average yield per mu, per capita grain, per capita taxes, population increase and land increase, etc., these data are compared like Changle said, you will know how many problems arise in the Tang Dynasty.

"Do you think your math book in Changle can be widely learned in the Tang Dynasty?" Li Shimin thought for a while and asked.

"Father, I actually think the knowledge in this math book is not much better than our Nine Chapters of Arithmetic, and of course it is not completely none. However, the great man used a brand new number called Arabic numerals and the letters that act as pinyin between them, which can represent many meanings, which means that it will be more convenient and convenient when recording the account book and operations."

"Actually, I think our Tang Dynasty mainly lacks a large number of talents in this area and lacks the application of these mathematics." Changle said seriously.

"So, do you think the Tang Dynasty Royal Private School can cultivate a large number of talents in this field?" Li Shimin immediately reacted.

"Yes, my father, I think it's OK, because the talents cultivated in this way, first of all, their impact on the top ministers of the Tang Dynasty should not be too great, so they should not cause much response."

"Also, their training speed is actually very fast. For example, in terms of basic statistics, you can devote yourself to the grassroots work in about one to two years of mathematical foundation."

"These people can be used as a large number of officials." Changle's little face was very serious. Obviously, she had thought about these issues carefully.

"It's right." Li Shimin nodded, and then he looked at Changle. The thought that had been dispelled before couldn't help but emerge again. Li Shimin had indeed not paid attention to Changle's changes, but he knew that before Changle communicated with Huo Gang, she was definitely not so smart, nor could she say that she was not so smart, but her perspective on the problem was not so broad.

Obviously, Changle is now standing at a very high angle. She looks at the overall perspective, and this angle is the most important for an emperor!

And who trained these?! Huo Gang!

And it was cultivated through letters just. As the crown prince of the Tang Dynasty, Li Chengqian was actually very smart. Li Shimin naturally paid much more attention to Li Chengqian than Changle, and he naturally had a much better understanding of Li Chengqian.

Originally, because of Changsun Wuji and others' words, Li Shimin's idea of ​​Li Chengqian and Huo Gang learning had fallen out, but now, his idea has emerged again and it is still rising!

If Li Chengqian could learn this, it means that at least the next generation of the Tang Dynasty would be strong! The Tang Dynasty would be strong too!
Chapter completed!