In fact, here in the magic capital, Consul Bafur is an artillery captain, and must have received a more systematic mathematical education, and the others, including foreign bank staff and missionaries, are at most only at the level of later primary school students, and it is easy to fool Chinese who have not seen mathematics, and it is probably difficult to follow the 21st century students trained by the sea tactics.

Of course, the above is just Zhao Dagui's own arrogance, and reality will soon slap him in the face.

"Let's talk about a simple question first, one plus two plus three plus four plus five, all the way up to a hundred, how much is it?"

"Five thousand and fifty. ”

As soon as Wang Tao finished speaking, Zhao Dagui didn't raise his eyes, and gave the answer directly, and then the two of them stared at each other with big eyes.

Wang Tao thought that his question was very difficult, and he could stump Zhao Dagui, and he had to find a pen and paper to calculate, but he didn't expect the other party to give the answer directly, and he felt like he was blocked in his throat when he landed.

"Hehe, this question is easy, Brother Zhao has calculated it before, right. Wang Tao felt a little embarrassed, scratched his head, and asked a second question: "Then count the second mention, which is similar to the previous one, from one plus two plus three plus four, all the way to one thousand, how much will it be?"

"Five hundred thousand and five hundred. ”

Zhao Dagui still gave the answer instantly, and then glared at Wang Tao, thinking to himself Are you a tease invited by a monkey, what kind of question is this.

The guest named Li Xinlan looked at Wang Tao and Zhao Dagui with wide eyes, and suddenly slapped the table and laughed loudly, laughing breathlessly.

"Brother Zhao has seen these two questions before, right?" Wang Tao suddenly reacted and pointed at Zhao Dagui and said.

"How fresh, I haven't even seen these two questions, and the junior high school math teacher will have to beat me to death. Zhao Dagui couldn't help laughing when he saw Wang Tao's expression, and accidentally leaked a little bit of heavenly opportunity.

"What is junior high school, well, that's not the point. Brother Zhao is really knowledgeable, and he knows such a remote question.

Then how about looking at this question again, from one to two to three, and then all the way to three hundred and twenty-seven, how much is it?" Wang Tao's face was purple and swollen, and he gritted his teeth and said.

"Well, this is a bit difficult, and you have to use pen and paper to calculate it. Zhao Dagui's curiosity was also aroused, he picked up a pen and paper and calculated it according to the formula.

The formula for the equal difference series was not invented until 1787 by the then ten-year-old mathematician Johann Carl Friedrich Gauss, and then gradually became familiar to the world.

(Note: This is the real child next door, ten years old, ten years old)

The Qing people, who have been isolated from the West for a long time, should not know the equal difference series, but Wang Tao obviously wants to teach the summation formula of the equal difference series, which is interesting.

Zhao Dagui took a pen and paper, wrote the calculation formula on the paper, and wrote out the answer, and the answer would naturally not be wrong.

"How come, you actually know how to stack and accumulate techniques?" Wang Tao and Li Xinlan didn't need to verify Zhao Dagui's answer, they just glanced at the formulas he listed, and shouted in surprise.

"What kind of stack?" Now it was Zhao Dagui's turn to be a little confused.

"Zhao comprador also knows mathematics?" Mai Dusi was originally watching the interaction between the three Chinese with a smile on the side, and after reading the number formula written by Zhao Dagui, he couldn't help but be surprised.

"That's the case, Brother Fang wrote a book on stacking analogy, which specializes in explaining this kind of topic, I thought it was unique in the world, but I didn't expect Brother Zhao to know it. It took Wang Tao a while to explain.

"And such things, can you let me read that book?" Zhao Dagui's interest was really aroused, and he hurriedly said.

Li Xinlan handed him a book on the table.

Zhao Dagui couldn't wait to pick up the book and read it, it was really a book that explained the summation method of the equal difference series, and it was not just a simple equal difference series, it should be regarded as a high-order equal difference series formula, which was much more difficult than a simple sum of one to one hundred.

Zhao Dagui didn't know how to solve many of these formulas, and Zhao Dagui should have seen some formulas, but he had forgotten them because he hadn't been in contact with them for a long time, and it seemed that the math teacher was really wronged.

"This is a book written by Brother Jingfang himself, and it is really profound. Zhao Dagui slowly put down the book and said to Li Xinlan, his eyes shining like electricity.

"Brother Zhao has seen all of these stacks, right?" asked Li Xinlan suspiciously.

"That's not it, I've seen some of the simplest things, and the more difficult ones won't be solved. Zhao Dagui told the truth.

"I see, but that's pretty good. Li Xinlan was a little relieved.

"Has Mr. Jingfang always studied these equal difference sequences?" Zhao Dagui unconsciously brought honorifics in his words, a modern mathematician in the Qing Dynasty, a very good identity.

"You say that this stacking problem is a series of equal differences, I don't know which family it is, but it seems very appropriate.

In addition to stacking, I have also studied the sharp cone technique, and I hope that Brother Zhao will correct it. Li Xinlan already regarded Zhao Dagui as a Westernist like herself at this time, so she took out another book and handed it to Zhao Dagui to read.

Zhao Dagui picked up the book and found that it was full of many strange mathematical terms, which were very different from modern normative terms, but combined with mathematical formulas, etc., he could barely understand the general idea.

It's just that after a cursory reading of this book, the doubts in Zhao Dagui's heart are deeper, the shock brought to him by this book is even worse than the stacking analogy just now, this is going to heaven.

Zhao Dagui is only a student of a third-rate university in modern times, but he is a science student and has received a systematic mathematics education, at least the ravages of advanced mathematics that must be experienced in college, and he must have felt it.

This book, called "Fang Yuan Explained", says it is about the cone, but in fact it is about calculus, which is an attempt to solve the calculus problem in a rather obscure cone way.

"I want to ask Mr. Jingfang for advice, this book seems to be very close to calculus, why should it be called a sharp cone?" Zhao Dagui asked cautiously.

"Sure enough, you can't hide it from the Fang family. Li Xinlan slapped her thigh and jumped up happily: "I think the sharp cone technique is similar to Western calculus, and Mr. Zhao feels the same way."

When I was young, I studied cone, and I thought it was quite profound, but in recent years, I have obtained some books from the West, and I learned that foreigners have the theory of calculus, and they have gone far in this regard, but Chinese people don't know it.

Mr. Zhao knows this, so he should know something about calculus. ”

"I guess there are some. Zhao Dagui smiled bitterly, it was almost the same as being ravaged, "By the way, I have a question for Mr. Jingfang, who else is riding a white horse besides the prince?"

"Tang Seng!" Li Xinlan couldn't help but be stunned, almost blurted out an answer, and looked at Zhao Dagui with strange eyes.