Ling Wudao smiled, as if he was a kind old man, looking harmless to humans and animals, but Yang Xuan believed that as long as he showed the slightest intention of wanting to escape, he might face a thunderous attack.

If it was just him, he could give it a try and see the power of the half-step humanity, but don't forget, there is still a Meng Qingqing behind him at the moment.

Meng Qingqing has always been extremely smart and did not speak, although she didn't know why Ling Wudao would call Yang Xuan Mr. Ren, but she knew that keeping her mouth shut at the moment was the best choice.

"It's better to be respectful than to obey!" Yang Xuan groaned for a moment, and then arched his hand.

Ling Wudao showed an extremely relieved expression on his face, and said with a smile: "That's very good, Mr. Ren, please!"

"Please!" Yang Xuan said.

However, after a while, Yang Xuan returned to his hometown, this time he didn't have to sneak around, but he still couldn't see the whole picture of the Biyun Sect clearly, and it seemed that the entire valley was shrouded in a layer of fog.

"Mr. Ren, please!" Coming to a hall, Ling Wudao fell down first and stood at the door.

Yang Xuan and Meng Qingqing also fell, and entered the hall with the order.

After the guests of honor were seated, their own servants served tea to the three of them.

Ling Wudao looked at Yang Xuan, and suddenly smiled: "Mr. Ren, it's not a secret, Ling has also studied a certain logarithmic technique, but compared with Mr., it is naturally far behind." ”

Yang Xuan couldn't guess what kind of medicine he was selling in his gourd, so he smiled and said: "To make the seniors polite, the number of techniques is broad and profound, and Ren is just a superficial taste, which is really not worth mentioning." ”

Ling Wudao laughed and said: "Mr. Ren doesn't have to be modest, Ling is really interested in the imaging method proposed by Mr. Ren, I don't know if Mr. Ren can answer one or two questions for Ling?"

Yang Xuan's heart was shocked, and he said secretly: It's coming.

At this time, he was also very curious in his heart, he didn't know why this Biyun Sect was interested in this?

But the knowledge of similar shapes, he had already told Zhang Heng and others, it was really nothing, and after a little hesitation, he explained in detail to Ling Wudao some knowledge about similar shapes in proportion.

After speaking, he obviously saw that Ling Wudao's face had changed.

Ling Wudao's original face was extremely flat, but now, his face was full of irrepressible excitement.

"Mr. Ren, wait a moment, there is a person in my Biyun Sect, who is a master of mathematics, presumably he and Mr. will be able to see each other at first sight. ”

After that, he didn't wait for Yang Xuan to answer, and walked out directly.

At this time, there were only two people left in the hall, Meng Qingqing and Yang Xuan, Meng Qingqing asked Yang Xuan with his eyes: What should I do?

Yang Xuan shook his head and motioned to Meng Qingqing to calm down and act when the opportunity came.

Although Meng Qingqing was sometimes not in tune, she also knew that the two of them were already involuntary at this time, she glanced at Yang Xuan apologetically, and her lips moved slightly.

Yang Xuan swept it a little and knew what she said.

What Meng Qingqing said was: You don't have to come to save me.

Yang Xuan smiled and shook his head, but didn't say anything.

Meng Qingqing still wanted to speak, but suddenly shut up, and the next moment Ling Wudao had already led a person in.

It was an old man with messy hair, deep-set eyes, red eyes, and a mustache under his chin that was glued together, as if he hadn't taken care of it for a long time.

"Mr. Ren, this is Elder Xie Tianji Xie of this Biyun Sect, Elder Xie, this is Mr. Ren. ”

Yang Xuan's heart was shocked, Ling Wudao was already the deputy head, under one person, above ten thousand people, he could be called Xie Lao, and his importance was self-evident.

He keenly sensed that this Xie Lao was probably a very important figure in the Biyun Sect.

"It's really a bad day, any cat or dog can be called Mr.?" Xie Tianji blinked his little eyes, looked at Yang Xuan with disdain, and then said to Ling Wudao: "Wudao, you too, how precious is my time, so do you have to waste effort?"

Ling Wudao smiled awkwardly at Yang Xuan, and then said to Xie Tianji: "Old Xie, this Mr. Ren is a great talent in the world, and when will Mingyue be written by Mr. Ren." ”

Xie Tianji sneered: "It's just playing with words, since ancient times, literati and ink writers have not had a good thing, and the better the literary style, the less it is a thing." ”

Yang Xuan was a little speechless, this old man surnamed Xie really didn't seem to have a good impression of literati, opening his mouth and closing his mouth was not a thing, but he Yang Xuan was really not a literati, he was really wronged.

Ling Wudao shook his head helplessly and said: "Old Xie, Mr. Ren also has deep attainments in mathematics, and his research on Old Xie must also be helpful." ”

Xie Tianji was slightly stunned, looked at Yang Xuan, and then sneered: "Mathematics, broad and profound, can a cat or dog come out at random, and can be said to be proficient in mathematics with a little bit of settling scores?"

Ling Wudao was speechless, and looked at this stubborn old man a little helplessly.

Yang Xuan smiled and said suddenly: "It seems that Xie Lao is above mathematics, and he must be very accomplished, Ren wants to ask Xie Lao for advice." ”

He already keenly felt that the safety of him and Meng Qingqing might fall on this Xie Tianji, who had no one in his eyes.

Xie Tianji looked at Yang Xuan with his nostrils and said, "Do you want to teach me, boy, you are not qualified enough." ”

Yang Xuan thought for a while, and suddenly said: "Old Xie, I have a question, today there is a wall five feet thick, two rats wear each other, one foot a rat a day, a mouse is also a foot, a rat is twice a day, and a mouse is half a day." When will we meet?

This question is a question in "Nine Chapters of Arithmetic", which means that two rats penetrate a five-foot wall at a speed of one foot per day, the big mouse has great strength, and the speed doubles every day, and the little mouse lacks stamina, and the speed is halved every day, and asks them when they can meet and how many feet each passes through the wall?

Xie Tianji was slightly stunned, and then said with a smile: "This question is also interesting, but if you are only at this level, it is not too much." ”

Then he squatted down, took out a piece of powder from his pocket, and wrote and drew directly on the bluestone floor.

After a while, he stood up and said, "This question is also interesting, two days of seventeen, two rats meet, the rat penetrates the wall three feet seventeen and eight, and the mouse passes through the wall one foot seventeen and nine, I don't know if my answer is right?"

Meng Qingqing's watery eyes widened, as if listening to a book from heaven, she understood every word that Yang Xuan and Xie Tianji said, but when they were connected, she didn't know what it meant at all, as if she was listening to a book from heaven.

Ling Wudao was a little better, and finally he heard Yang Xuan's question clearly, but until now, his mind was still a mess, let alone solving the answer.

Seeing Xie Tianji say the answer, Ling Wudao's gaze immediately fell on Yang Xuan.

Yang Xuan was in awe.

Even if he used modern methods to calculate this problem, it would take a lot of effort, but Xie Tianji drew some symbols on the ground that he didn't even recognize, and it only took a moment to get the correct answer, which was incredible.

At this time, he immediately understood that this thank heaven was probably the extremely rare mathematician in this world.

Xie Tianji saw Yang Xuan's surprised face, and said with a smug smile: "You can ask such a question about mathematics, it seems that you do have some attainments in mathematics, since this is the case, you can also listen to my question." ”

Xie Tianji opened his mouth and said: "I don't know how many things are today, there are two left in three or three, three in five, and two in seven or seven." Ask about the geometry of things?"

Yang Xuan was slightly stunned, the problem of not knowing how many things are there?

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