The more the three of them thought about it, the more they felt that the person was Zhang Gongchuo. You know, before Zhang Gongchuo lived in seclusion, he was also very concerned about the people, so he had a very good reputation among the people.

He once refuted a senior official at that time in the court without fear of power, and implemented the latest calendar, providing a relatively more accurate basis for the people to farm.

Unfortunately, he was framed later and lost his official position. In the end, he had to return to his hometown and continue to study the calendar and weights and measures. In fact, it is not only said that mathematical techniques are developed separately.

It is better to say that the development of mathematics is because of the need to study the calendar and weights and measures, so it has to develop accordingly. Mathematical techniques have always been born to solve problems.

...

In the hall of Li's mansion.

Zhang Gongchuo also started a topic first and said: "I wonder if I can borrow all the process of calculating the other product you just now."

Li Zong signaled Xiaoqing to take it over and replied, "Of course this is OK! Xiaoqing, take it over to you two."

Zhang Gongchuo then said, "I don't know why I want to build this new symbol. To be precise, how did I think of doing this."

Li Zong said: "Of course, I don't know how to use calculation chips, and I think calculation chips are troublesome. The multiplication of calculation chips is easy to understand, but division is very difficult to understand."

"Five years ago, I got a serious illness and could only sleep in bed all day. Since I was bored at that time, I remembered whether to study this."

"So, that year, I unexpectedly thought of it, or use some symbols that I feel are easy to use to re-establish a set of mathematical calculation systems."

"Because when I was about to name this day, I happened to say something inexplicably, and Ning Bo passed by again by chance, so I decided to name these symbols as Arabic numerals."

"There are only ten Arabic numerals in total, but using these ten symbols can represent the vast majority of the numbers in the world."

"I believe that both of you have seen how fast and accurate my calculations have just happened, but this is not all my mathematical research."

In fact, if it were normal, Li Zong would definitely not say that. He would seem a little arrogant if he said so.

But now he has finally found someone to listen to his own teachings. It is so difficult. In order to keep the other party, he has to show a little confidence.

Even though the two people he heard about at this time were just two old men over fifty years old.

But it doesn't matter to the old man. His principle of teaching people is to not ask about age or men or women.

Heng Xun also said at this time: "It can be seen that this method is indeed more than twice as fast as using calculation chips. And we all knew before we came that when we encounter a suitable number, my friend's calculation speed can be faster than this!"

Li Zong was embarrassed, "It seems that he already knows it. So what do you guys come here today and want to know?"

Heng Xun said: "First, it's this kind of calculation method, and secondly, we both have some questions about your quick calculation method."

Zhang Gongchuo: "For example, subtraction, one multiplication, one. I have studied books related to numerology since I was a child. I have only seen addition and subtraction of subtraction, but I have never seen subtraction, one multiplication and one. I seem to have also studied negative numbers?"

Li Zong said: "Cough! Very shallow and shallow research."

Heng Xun: "Subtract one multiply and subtract one, why is the product one?"

Li Zong thought about it and said that this is not a primary school student, no, he should be in junior high school. Isn’t this what all junior high school students understand?

Li Zong: "Subtraction one multiply and subtract one, actually the correct way to call it negative one multiply and negative one. Your subtraction one should be heard from Erlang, an insider. As for why the accumulation is one, this is probably a common thing. Or you can understand it this way, using the first negative one means that A owes B a copper coin, and using the second negative one means that it is a day ago. So according to this, negative one multiplying one means that B can finally get a copper coin from A. So multiplying the two is one, changing the two negative ones into negative five, that is, A owes B five days and has a copper coin every day. Finally, you have to ask how much copper coin A owes B, and the answer is negative one times and negative five, five. B cannot be negative, owing A five copper coins."

Li Zong: "If you say that, it may be difficult for both of you to understand..."

"Then we can also go back to the question itself, that is why there must be such a formula (a-b)(c-d)=ac-ad-bcbd."

This is going to draw a picture.

Li Zong drew the picture after brushing it a few times.

Immediately afterwards, I briefly explained to the two.

The two of them suddenly stared at Li Zong as if they were looking at monsters.

Because this is the first time they have seen each other, there is such a concise and easy-to-understand proof in the world.

This is not a genius, what is it!

No!

This man is simply a genius!

Li Zong saw one of the old men's throats moving, thinking that he was going to pounce on him.

He was not as excited as the other party on the day of his wedding, okay!

Move back quickly.

Unexpectedly, the other party suddenly burst into laughter.

Haha laughed and said, "My friend's method really breaks my past common sense."

That's right!

It should be broken here, and it should be the kind of cracked him with a stick and smashed him to death.

After Heng Xun also took over the other party's words and said, "This kind of proof has never been heard from ancient times to the present! I can make sure that my friend is definitely the first one!"

Li Zong also bowed and said, "The words are so heavy, the words are so heavy! It's just that I just happened to be a little tricky."

Zhang Gongchuo reached out and said, "No! My friend is too modest! I dare say that no one has ever used a similar proof method except me. Moreover, this method is suitable for everyone, so it is to let the most stubborn people come to see you, and I'm afraid I have to believe it."

Li Zong said: "As long as you can understand it, I am worried that this method cannot convince two digits. However, this method is not completely applicable to all. If there is any method to prove it, then there is probably only one left. Because negative numbers represent inverse, the negative number can be understood first as a negative number multiplied by a positive number and then inverse, so it will be positive. Negative numbers should not be simply understood as a number. Negative numbers have directions, and negative signs represent directions rather than sizes."

Zhang Gongchuo: "It makes sense! In this way, the words just now can be understood as I owed my friend a copper coin, and then I only owed me once. Originally, I should have owed me a total of one copper coin at this time, but now the direction has changed. I owed me now and then I should have borrowed it. I once lent my friend a copper coin, so I should give me a copper coin next, and I should also get a copper coin in the end."
Chapter completed!