Empress Changsun didn't let Changle say this, obviously she didn't really let her say it, just to relieve Li Shimin's embarrassment. If Li Shimin still needs her eight-year-old girl to teach these things, where will Li Shimin's face go.

"Huo Gang taught you these things?" Li Shimin thought about it and asked directly, but he didn't care, there was no one else here, and several maids were also personal maids, so they didn't dare to say these things casually.

"Yes, these are the knowledge in the mathematics book he gave me, and he said that mathematics is the foundation of all things, and almost everything in the world can be calculated by mathematics. For example, how much grain Datang earns each year, how much Datang's tax revenue has increased, how much Datang's population has increased, and then what is Datang's average population tax revenue, and what is the average per capita income, all of which can show whether Datang's national strength is rising or falling. Changle said seriously.

Li Shimin was stunned for a moment, the data that Changle said were actually counted by the household department every year, but the results of the household statistics were not so detailed.

"Tell me more." Li Shimin is very interested, because this is definitely necessary for the future development of Datang.

"Father, let me give you an example, if Datang's annual tax revenue this year is 2 million yuan, and Datang's income next year is 2.2 million yuan. If Datang's grain income increases by 1 million stone next year, do you think Datang is getting better? Changle immediately asked.

"Of course it's getting better." Li Shimin immediately spoke.

"No, Father, that's not accurate." Changle immediately spoke.

"Why isn't it accurate?" Li Shimin asked rhetorically.

"It's very simple, you have to see how much Datang's population has increased, for example, Datang's population this year is 30 million, and the tax revenue is 2 million, but next year's Datang's population will increase to 33 million, but Datang's annual tax revenue next year will be 2.2 million, in fact, if Datang's per capita tax revenue is counted, it has not increased, which means that Datang's national tax growth has come to a standstill, which is definitely not good news for the whole country, which means that Datang has a problem."

For example, we have a population of 30 million in Datang this year, a total of 100 million mu of cultivated land, and a total income of 220 million stones. If the population of Datang increases to 33 million next year, the total cultivated land increases to 200 million mu, but the total income of grain is 300 million stones, which means that although the grain of Datang has increased, the average grain income per mu of land has decreased. ”

"At this time, my 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 someone is filling their own pockets, etc."

"If it's the climate, or other problems, then the emperor needs to think about disaster relief in advance, because there will be no food problems for the time being, then maybe the climate will change significantly in the future."

"If there are frequent disasters such as famine in a certain area because there is too little arable land per capita, you can consider emigration of the population of this area." Changle explained seriously.

These are all things that she has worked hard to learn, which is no longer purely the category of mathematics, of course, you are also right when you say mathematics, in fact, this is already related to the knowledge of statistics and other aspects.

In this era, although the Tang Dynasty would also count similar data, only the overall data, and the per capita data were not possible, because the Tang Dynasty did not have so many arithmetic talents.

It is hard for you to imagine that the budding of mathematics in China is ahead of the world, but the development of mathematics is lagging behind the world, and this depends on the way ancient China wrote down.

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

In this way, it is difficult for future generations to get inspiration from the derivation of their predecessors, and even some later arithmeticians are more powerful, when they use the formulas and results of their predecessors, they themselves have doubts and need to prove themselves, which wastes the energy of many arithmeticians.

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

In fact, the nine chapters of arithmetic appeared around 100 AD, but you dare to believe that after the mathematician Zu Chongzhi of the Northern and Southern Dynasties, mathematics in the Sui and Tang dynasties was almost always in a state of stagnation.

Therefore, affecting the development process of each civilization, maybe a small factor may affect a lot, a bamboo slip record will affect the development of mathematics, and the West because of the small number of people, more use of animal skin records, so you can record the graphics and texts in detail, study the geometry, and then gradually record the process, and many subsequent 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, and this kind of result 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, but in fact, in history, many simple mathematical laws may not be discovered, but some rare ones have been discovered.

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

Therefore, it is very necessary for future generations to summarize.

And the mathematics that Huo Gang came up with is actually a perfect mathematical system in later generations, so it is very important.

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

However, some of the knowledge in the nine chapters of arithmetic is difficult, and it is not suitable for universal learning.

The most important thing is that the knowledge of this system is the most important, especially the application scenario, these are the key things.

Li Shimin only needs to think carefully about these things to know how useful they are, just like Changle said, if you figure out all these data in a county, then if these data fluctuate too much next year, you will immediately know that there must be some problems in this county.

But it's not easy to calculate these figures, because it means a large number of people who know how to do arithmetic.

Li Shimin suddenly thought of what Wei Zheng had reported to him in detail before, more than a dozen departments of the Han Dynasty, these departments have nothing to do with the political system of the Han Dynasty, but from the names of these departments, it can be seen what these departments do.

One of these departments in Dahan is called the Audit Department, and this Audit Department is probably doing these jobs, so that Dahan's control over his entire country is far greater than Li Shimin's understanding of Datang.

To be honest, if it weren't for what Changle told him, Li Shimin wouldn't have imagined how much effect these data would have on Datang, but as soon as Changle said this, he understood how much effect these data had on Datang.

Just like the average yield per mu, per capita grain, per capita tax revenue, population increase and land increase, etc., these data are like what Changle said, and we all know how many problems have occurred in Datang.

"Changle, that math book of yours, do you think our Datang can be popularized and learned?" Li Shimin thought for a while and asked.

"Father, in fact, I don't think the knowledge in this math book is much better than our nine-chapter arithmetic, of course, it doesn't mean that there is nothing at all, but Dahan has adopted a new kind of number, called Arabic numerals with those letters that act as pinyin between them, which can represent a lot of meaning, which means that it will be more convenient and convenient when recording the ledger and calculating."

"In fact, I think that we in Datang mainly lack a large number of talents in this area, and lack the application of these mathematics." Changle said seriously.

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

"Yes, father, I think it's okay, because the talents cultivated in this way, first of all, their impact on the top ministers of the Tang Dynasty should not be too big, so there should not be many repercussions."

"What's more, their training speed is actually very fast, such as basic statistics, about one to two years of arithmetic foundation can be put into grassroots work."

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

"That's a good point." Li Shimin nodded, and then he looked at Changle, and the thought that had been dispelled before couldn't help but pop up again, Li Shimin really didn't pay attention to the changes in Changle, but he knew that before Changle communicated with Huo Gang, she was definitely not so smart, and it can't be said that she wasn't so smart, but her perspective on the problem was not so broad.

Obviously, the current Changle has stood at a very high angle, she sees the perspective of the overall situation, and such an angle is the most important for an emperor!

And who cultivated these?! Huo Gang!

And it was cultivated just through letters, as the crown prince of the Tang Dynasty, Li Chengqian is actually very smart, Li Shimin's attention to Li Chengqian is naturally much higher than Changle's, and his understanding of Li Chengqian is naturally much more.

Originally, because of the words of the eldest grandson Wuji and others, Li Shimin's idea of letting Li Chengqian learn from Huo Gang had fallen, but now, his idea has come out again, and it is constantly rising!

If Li Chengqian can learn this, it means that at least the next generation of Datang will also be strong! Datang will also be strong!

"Guanyin, I have an idea I want to discuss with you." Li Shimin suddenly spoke.