"Li Jijiu, forget it if you solve the problem. Today I came here to ask you some questions about that lens. That day, I saw my aunt sending grandfather a pair of reading glasses, which could allow him to see what was close to him. Is this the reason?" Li Chengdao was not interested in Li Xiu's suggestion that he asked him to solve the problem. After all, in his opinion, Qi Niang, who was a few years younger than him, would definitely only do some basic questions, and there was nothing to calculate at all. It was the problem of reading glasses that made him more interested.

"Haha, the principle of reading glasses cannot be explained clearly in just one sentence or two. If you want to thoroughly understand the principles, you must have an extremely advanced mathematical foundation. So the prince should solve the problem before talking about it!" Li Xiu said with a faint smile. The principle of reading glasses seems simple, but it is a physical optical problem, and it also involves calculations such as light refraction, so Li Xiu is correct that he needs a mathematical foundation.

When Li Xiu said this, Li Chengdao was also a little skeptical. At this time, Princess Pingyang said with a serious expression: "Daoer, since you want to come to Li Jijiu for advice, you must obey Li Jijiu's arrangements, otherwise you might as well go back to the palace to learn from the masters!"

"Yes, my nephew understands!" Li Chengdao finally woke up after hearing his aunt's words. After saying that, he bowed to Li Xiu again, "He was a little confused just now. I hope Li Jijiu won't blame me. I'll solve the problem now!"

After Li Chengdao finished speaking, he was about to go to the pavilion, but then Princess Pingyang said again: "Dao'er, since you ask Li Jijiu for advice, although you have not really become a disciple, you can't be too unfamiliar. I think you just call Li Jijiu Mr. Li Jijiu, and Li Jijiu doesn't have to be too polite to Dao'er, just call him by his name!"

"What my aunt said is, Chengdao pays homage to Mr.!" Li Chengdao was extremely clever and immediately changed his name to politely to Li Xiu when he heard this. Speaking of which, his grandfather Li Yuan just agreed to ask him for advice from Li Xiu, but did not let Li Xiu be his teacher, so it was very appropriate to call Li Xiu "Mr.".

Princess Pingyang said this, and Li Xiu couldn't refuse any more. He always wanted to respect Li Chengdao as the prince. He also felt a little uncomfortable, so he replied casually: "Chengdao, you don't have to be too polite!"

Seeing Li Xiu agreeing, Li Chengdao was also very happy at the moment. Then he bowed and left again and came to the pavilion to look at the topic. Qi Niang was lying on the table and biting the tip of the brush with a tangled expression on her face. After Li Chengdao came in, she just glanced at him and then continued to bite the tip of the brush. This question was still a bit difficult for her and she had not yet figured out her thoughts.

Looking at Qi Niang's entangled expression, Li Chengdao smiled calmly. He was quite confident in his math. After all, he didn't think Li Xiu would have any problems for a child like Qi Niang. However, the smile on Li Chengdao's face did not last long. When he saw the question in front of Qi Niang, he was stunned for a moment because he couldn't understand the question. To be precise, he didn't recognize some things like ghost drawing talismans at all, but he could understand the others.

Li Chengdao never expected that he could not even be stunned by the topic. He wanted to go back and ask Li Xiu, but he saw that he seemed to be very happy to talk with his aunt, and he couldn't even understand the topic. This made him feel embarrassed and embarrassed to ask Li Xiu, which also made him look entangled.

But Li Chengdao soon discovered the turning point of things, because he saw that there were many similar symbols written on the draft in front of Qi Niang, which showed that she must have known each other, so he finally asked softly with shameless face: "Little sister, what do those symbols on the topic mean?"

Qi Niang was thinking about the key to this question, but suddenly she was interrupted by Li Chengdao and was very unhappy. She gave him a blank look and said, "Have you never played cards?"

"Cards? I seem to have heard of them, but I haven't played them?" Li Chengdao said embarrassedly at this time, because when Qi Niang spoke, it seemed that everyone could play cards.

"It's so pitiful, I can't even play cards!" Qi Niang looked at Li Chengdao with some sympathy when she heard this, then picked up the brush and wrote ten Arabic numerals on the paper, and said, "Okay, you can read it yourself, and ask if you don't understand."

This was the first time that Li Chengdao was said to be pitiful, and the other party was a girl a few years younger than him, which made him blush and he didn't even dare to look at Qi Niang's eyes. He had to stare at the numbers on the paper and remember them one by one in his heart.

Li Chengdao had a mathematical foundation and was extremely smart. So after knowing ten numerical symbols, he asked Qi Niang about the rules of the arrangement of numbers and quickly understood the meaning of the question. However, after understanding the question, a little bitter smile appeared on his face again because he could not solve the question.

Mathematics in ancient China were also very developed, and even the round ratio could be calculated early. However, the ancients paid far less attention to mathematics than literature. Although there were also mathematics subjects in the imperial examination, they were definitely not comparable to that of Jinshi. Even the emperors like Li Chengdao had their main energy on the education of Confucian classics and current affairs. They only learned one foundation for mathematics. As for the one-center equation in front of them, he really didn't know how to solve it?

Li Chengdao couldn't understand it, but Qi Niang's eyes suddenly lit up at this moment. She finally thought of the key to this principle. She began to calculate it carefully on the paper, and finally got a correct result. In order to ensure it was correct, Qi Niang checked it several times. Finally, she finally confirmed that this was the correct answer. She cheered and ran to Li Xiu to take the credit with her own verification process.

Li Xiu took Qi Niang's verification process and found that although she did not substitute an unknown number, she used another complicated method to solve the problem, which was very good. At that moment, he couldn't help but praise Qi Niang: "It's good, Qi Niang, you are indeed very smart, but don't be proud, because there are more simple ways to solve this problem."

As soon as Li Xiu finished speaking, Li Chengdao also walked over with a dejected look and said, "Mr. Qibing, I can't solve this problem!"

Princess Pingyang saw that Li Chengdao actually gave up, but Qi Niang solved it. She was very curious at the moment. She took the question from Li Xiu and looked at it. As a result, her long eyebrows frowned suddenly because she felt it was a bit difficult for this question. She thought hard for a while before she came up with a solution.

"Li Jijiu, is it too early for Daoer and the others to do such a difficult question?" Princess Pingyang said softly at this time. She felt that maybe Li Chengdao would be more suitable for such questions when he was a few years older.

"Princess, this is actually a very basic problem, and its solution is actually very simple. I want to teach Qi Niang and the others now, and you will understand it after reading it!" Li Xiu said with a smile. If this problem is solved with traditional thinking, it is indeed very troublesome, but if you list a one-to-one equation, it will become extremely simple.

Li Xiu said as he picked up the pen, then began to list the equations on the paper, and then wrote the solution. The result was obtained in two simple steps, which also made Princess Pingyang, Qi Niang and others a little stunned. However, Princess Pingyang raised her own question and said, "Li Jijiu, what does the fork you drew mean, and what do those crosses and two horizontal lines mean?"

Although Princess Pingyang knew Arabic numerals, she did not know the meaning of the calculation symbols, so she could only see that the result was correct, but she could not understand the calculation process. The same was true for Li Chengdao next to her. Li Xiu also patiently explained this thing. This thing seemed very simple to later generations, because later education had long laid a solid foundation. Now, Li Xiu wanted to explain it to Princess Pingyang and Li Chengdao who had no foundations, which took a lot of time.

It was until noon after the sun, Princess Pingyang and Li Chengdao finally understood Li Xiu's problem-solving process. Finally, Li Xiu concluded: "This question is actually a standard one-element equation. In the future, when encountering similar questions, you can substitute an unknown number to solve it. This is also the most basic. In the future, there will be one-element quadratic equations, two-element quadratic equations, etc., which are more difficult, but they are all developed based on this one-element quadratic equation!"

"So that's it. I didn't expect that math can be learned like this!" Princess Pingyang said with emotion after hearing this. Li Xiu's math ideas were completely different from those she had learned before. Moreover, after adding various symbols, the entire problem-solving process became simpler and clearer. The dispatch of food and supplies in the army also required calculations. If Li Xiu's method could be used, it would definitely greatly improve efficiency.

"Sir, it is really a blessing for Chengdao to be able to follow Mr. to study!" Li Chengdao was convinced at this time. Just one calculation allowed him to see the talent in Li Xiu's heart, and he was sure that these were just a corner of Li Xiu's talent, and there must be something even more amazing in his heart.

"Haha, these are nothing, they are just basic things!" Li Xiu couldn't help but smile when he heard Li Chengdao's words. He was deliberately shocking Li Chengdao to avoid him from accepting discipline. I believe that after this incident, he should respect himself, which will facilitate his future management.

"Brother, stop talking, my stomach is almost hungry!" At this time, Qi Niang said with some dissatisfaction. She had laid some foundations before by Li Xiu, so she had already understood the solution to this problem. It was already noon. Liu'er had visited them several times just now, but because Li Xiu was giving a lecture, he did not interrupt them. It was probably because lunch was hot several times now.

When he heard Qi Niang's words, Li Xiu and Princess Pingyang couldn't help laughing. In the following period, Li Xiu would give lectures to Qi Niang every day. Li Chengdao would come to listen to the class whenever he had time, but the courses he had fallen behind could not be made up. In the end, he didn't know how he bribed Qi Niang, and actually asked her to help him take notes. Princess Pingyang sent someone to the East Palace to Li Chengdao every day, so that he would not miss too many courses.
Chapter completed!