Zhao Ji sat back on a recliner.

Let the master craftsman match the shape of the wooden recliner to create a wooden recliner, Zhao Ji lying on it as if embedded in it, so that the paralyzed body will not fall left and right. At least face to face with his son.

'Sixth brother, one, one hundred, how much? ’

The words drawn by Zhao Ji on the sand table were intermittent, but Zhao Jian stood in the Funing Palace, just talking about the topic that Han Gang came up with. Yang Jian would not misunderstand what Zhao Jian wanted to say.

He relayed to Zhao Maid: "Your Highness, the official family is asking Han Shumi's question about adding to one hundred, and how much is it calculated after the last?" ”

"Five thousand and fifty."

Zhao Maid was a little embarrassed when she spoke.

He used more than an hour to calculate twice since the end of class, but the answer was not the same. Zhao Maid originally wanted to count it a third time, but Song Yongchen persuaded him, and Han Shumi said that he could ask others.

But Zhao only remembered that Mr. Han was referring to the two questions on the chessboard that could be asked to put wheat grains and rulers and hammers, and one was added to one hundred, which was to let him calculate it himself.

In the first question, he asked his mother, and in the latter, he came to ask his father. The last question, Zhao Maid still insisted on doing it herself. Because the queen mother asked him to listen to Mr. Han, and his father also asked him to listen to Mr. Han.

However, halfway through, Liu Weijian caught up and told him that there was an easy way, let him add one hundred, two plus ninety-nine, and all the way to fifty plus fifty-one.

Zhao Maid quickly figured it out, a total of fifty one hundred and one, and took the pen and calculated it, it was exactly five thousand and fifty. The result is the same as the first step by step added up.

Liu Weijian didn't tell him the answer, but if Liu Weijian didn't say it, Zhao Wei couldn't think of such a simple calculation method.

Zhao Maid didn't know how to calculate this, count it as his own, or help others? The child felt a little awkward.

'Right? Zhao Ji wrote.

"The slave and maid let people forget it. Four of the six reported five thousand and fifty. The prince should be right. Yang Jian replied in a low voice and smoothed the sand table with his hand.

Zhao Ji blinked, raised his hand and began to write again.

At this time, the people from the palace outside the door entered the palace to report, "Official, Master Su has arrived." ”

Su Song was a bachelor of Hanlin and a banquet official, who lectured on the history of the scriptures for Zhao Xu. He is a well-known erudite in the court, and he has been in contact with Han Gang for a long time, and he is also regarded as a lineage of qi.

Su Song was recruited into the palace, and he already knew what was going on in advance.

"It's in the center of gravity!" Su Song answered the Son of Heaven's inquiry.

Han Gang talked about the problem of the center of gravity in "Gui Window Cong Talk". Rulers, planks, boxes, and drunken traps[note 1] were used to illustrate what the center of gravity was.

If the weight of gravity is not moved out of the bottom of the weight, the box will not tip over. If the center of gravity of the board falls outside the tabletop, it will fall to the floor. If you sit on a chair and don't use your hands, you can't stand up without leaning forward, and if you want to get up, you have to shift your weight to your feet.

Su Song did the experiment with his own hands. And so it turned out.

The principle of the center of gravity perfectly explains why the embankment should be wide at the bottom and narrow at the top. And empty cars and empty ships are easy to capsize. Sumo wrestlers tend to be the winners for the stout ones.

Su Song spent half an hour, from beginning to end, explaining in detail to Zhao Ji and Zhao Maid, the father and son. And I also drew pictures and did a few small experiments.

Su Song's teachings are simple and easy to understand. Yang Jian, who was listening, also understood the truth, and had a feeling of sudden enlightenment, it turned out that the truth was so simple.

The reason why the ruler can't fall after hanging the hammer is because the center of gravity of this whole system—this is a rare word used by Su Song—is located under the table, in the projection of the table—a word that is also obscure, but easy to understand when explained—is actually equivalent to being placed on the table. The reason why a single ruler falls is because the center of gravity is outside the table and the force is unbalanced.

'Center of gravity'.

Yang Jian meditated in his heart, and also saw the Son of Heaven writing on the sand table.

Now that I think about it, these are the two words that Han Shumi wants to say.

I can't imagine that there are so many truths contained in a small ruler and hammer.

Grasping the center of gravity, what seems unbelievable is actually very common. The key is to grasp the truth.

Yi Yin said to Shang Tang, 'Governing a big country is like cooking a small fresh'.

Mao Chuan said: 'Cooking fish is annoying, it is broken, governing the people is troubled, and knowing how to cook fish is knowing how to govern the people', 'Cooking small fish does not go to the intestines, does not go to the scales, does not dare to scratch, and is afraid of its mince." ’。 "Huainanzi" and "Han Feizi" are also mentioned.

Even Emperor Tang Ming once commented: 'This metaphor is also. Small fresh, small fish also, words cook small fresh can not be scratched, scratch the fish collapse, Yu Li big country, can not be annoying, annoying people are chaotic, all must use the Tao, so the success of '

Cooking small fish as a metaphor for governing a big country is what Yang Jian learned when he was in school in the palace before. And now, isn't Han Gang using the theory of gravity as a metaphor for governing things? If you find your center of gravity, you can lift as much weight as you like.

Yang Jian asked himself if he understood Han Gang's thoughts.

The ancient sages liked to use metaphors to persuade the emperor, but weren't the disciples of the Medicine King just like them? It's well-intentioned.

From the eyes of his little eunuch, Wang and Cheng seem to be far inferior to their juniors.

In Yang Jian's eyes, the official family was also pondering, and it was not until a long time after Su Song left that he began to write again: 'Chessboard ......'

Yang Jian understands and asks people to find answers.

As a result, Yang Jian was dumbfounded, the smart prince tilted his head and became confused, and the Son of Heaven did not move for a long time.

Numbers far beyond the limits of imagination. At the beginning it was just one grain or two grains of wheat, and at sixty-four times the ...... Well, after sixty-four times, it's unbelievably huge.

Yang Jian realized in his heart.

This is also an exhortation.

In the township, there are often double interest rates in usury, which kills countless people. Yang Jian's family was poor when he was a child and did not enter the palace, so he had a deep understanding of this.

Think about it, as long as you borrow a penny, after 64 years, it will become a huge debt that the tax revenue of the Great Song Dynasty cannot cover for hundreds or thousands of years.

And if you borrow a few times normally, you don't need sixty-four years, and three or five years can kill people.

This is another irony of the Son of Heaven, who should suppress mergers and reduce people's loans. This is also the only way to let the prince, who grew up in the palace, know the suffering of the people!

The dynasty is virtuous, and the family and country are fortunate.

In reverence and excitement, Yang Jian saw Zhao Ji rowing in the sand table again:

'Tomorrow, recruit Han, and have a feast. ’

Han Gang's next class was supposed to be two days later.

It's not that Zhao Maid's class arrangement is unreasonable, but that important ministers like Wang Anshi and Han Gang make it unrealistic for them to teach the prince every day. As for Cheng Hao, because of the establishment of another Taoist system, the number of times he came to class was also pressed by Wang Anshi, and it could not be more - it is said that there are reasons why the queen does not agree.

Most of the time, the work of teaching the prince was left to other teachers in the Shizentang. From Wang Anshi, the highest status, to the lowest Xiaohuangmen, there are nearly 100 people serving in Zishantang. Etiquette, archery, and even the recitation and copying of scriptures such as the Analects are all handled by a separate person. Before Han Gang came back, there were other people who came to take the arithmetic class, Zhao Maid learned addition, subtraction, multiplication and division within a hundred at such a young age, and the eunuchs who grew up in the imperial city, among which there were many Yunwen Yunwu people, which also showed the level of royal teaching.

However, Wang Anshi, Han Gang and Cheng Hao are the princes hired by the Son of Heaven with an edict after all. Every day, in Zhao Maid's course, there is a key subject, either Wang Anshi, or Cheng Hao, and now there is Han Gang.

And now the sutra banquet that Zhao Ji is talking about is not a lecture for Zhao Maid, but it is for Zhao Xu, who is the Son of Heaven.

Wenchen talked about the history of reading the scriptures at the scripture feast, using the past as a metaphor for the present,

Yang Jian's face was embarrassed, and he persuaded softly: "Official, but your body? ”

Zhao Ji closed his eyes and didn't say a word, only tapped his fingers. Yang Jian bowed his head and bowed: "The slave and maid know the way." ”

……………………

Han Gang returned home early at this time.

Zhou Nan helped change clothes and wipe her face, Yun Niang served tea, and Su Xin also brought snacks made by herself.

All daily life is served by beautiful wives and concubines, who are comfortable and leisurely.

Compared with more than ten days ago, the days of hard work in Hedong are nothing less than clouds and mud.

In the evening, Wang Yi, who was invited by Wang Anli's wife to speak, rushed back, and saw Han Gang leaning on a rocking chair in the study and reading happily, and couldn't help laughing: "It's hard for officials to teach the prince. ”

"How is that possible?" Han Gang smiled, "It's the students who work hard." ”

Wang Yi's face changed when he heard this, and he asked repeatedly, "What's wrong?" Is it asking those tricky and outlandish questions again? Or let the prince go to raise silkworms and tadpoles to make records? Isn't it a quick calculation? ”

In Wang Yi's eyes, Han Gang has a criminal record.

Han Gang's questions for his children are often trickier than chickens and rabbits in the same cage, the two islands in the river, why don't you repeat the seven bridges connecting the island and the shore, if not, what is it for? Adults can't do it, he does it for children.

In order to cultivate the observation ability of children, let the eldest and second go to raise silkworms, since ancient times, men have cultivated and women have been weaving, worshiping Ma Tou Niang [Note 2] It should be a woman. I also caught tadpoles and raised them in a glass vase worth dozens of times, thinking they were frogs, but I raised a toad, and I cried my daughter who was full of expectations.

In the early days, as soon as I learned addition and subtraction, I began to ask for quick mental arithmetic. List a hundred questions from top to bottom, and see how much you can do after drinking tea, and you will be rewarded for completing it.

For the education of his children, Wang Yi quarreled with him several times, but Han Gang always spoke up, and finally made Wang Yi speechless.

"How so." Han Gang shook his head and denied, "This is the first class to be held for the Son of Heaven." How can it be the same as your own children? Today is to test which step the prince has learned, and the rest is to come up with three questions. ”

"What's the question?"

Han Gang raised his eyes, "I still remember the question that was added to one hundred at the beginning." ”

Of course Wang Yi remembers. The children in the family are all the results of death, and even Wang Yi himself didn't expect that there would be such a simple calculation method, but Zhou Nan quickly found the trick.

"What about the other two?"

"The other two questions are not for the prince to do, but for him to ask. It's much more interesting than the first one. "Han Gang sells Guanzi.

Wang Yi was about to ask carefully, when a family member hurriedly came, "Privy! The envoy came from outside, saying that he had been instructed by the Son of Heaven to ask the officials to go to the banquet tomorrow. ”

Note 1: Catching drunken immortals, tumblers in the Tang and Song dynasties. Place it on a plate at the banquet and turn it to persuade the wine according to its direction.

Note 2: Matou Niang is a silkworm god, originally a horse-headed human body, but the idol is mostly a girl wearing a horse's skin. There is a legend that a young girl was rolled into a silkworm by a horse's skin.