Meng Qingqing can go, of course Yang Xuan can''t.


    After the messenger persuaded Meng Qingqing to leave and told her not to tell her own things, Meng Qingqing reluctantly left with the order.


    However, Yang Xuan doubted whether she was reluctant to part with herself or snacks.


    After Meng Qingqing left, Xie Tianji continued: "brother Ren, you''d better explain the shadow measurement method."


    On this point, Yang Xuan didn''t want to hide, so he explained some related knowledge of similar shapes and proportions for Xie Tianji in detail. This explanation is even more detailed and further than the previous explanation for Zhang Heng.


    Xie Tianji obviously understood. After meditating for a moment, he sighed: "I heard the method of shadow measurement before and thought it was a path. Now I let my brother explain it, and I realized that this is also a path. My brother''s attainments in mathematics are really extraordinary."


    Then he said, "but what about the straight method of measuring the circumference?"


    Yang Xuan looked at Xie Tianji and said, "old Xie, do you know what the Qing Xue royal family got in exchange for measuring the Zhou Zhifa?"


    Xie Tianji was a little stunned, then his eyes fell on Yang Xuan''s fingers, smiled and said, "if brother Ren still wants a storage ring, I don''t have biyunzong."


    Yang Xuan didn''t wonder why he knew the secret of Xin. He shook his head and said, "old Xie laughed. It''s useless to store more rings. I just want one thing."


    Xie Tianji narrowed his eyes and said, "what?"


    Yang Xuan went straight up and down: "you sent a token from the elder Keqing."


    Xie Tianji was stunned. He was ready to listen to Yang Xuan''s lion. Unexpectedly, Yang Xuan made such a request.


    To tell you the truth, Yang Xuan''s request is nothing at all. On the contrary, it is good for his Biyun sect. Just think about it, a person with five Qi can be treated with dignity no matter which sect he goes to. It''s just something he can''t ask for. Unexpectedly, Yang Xuan put it forward as a condition.


    "What''s the difficulty? Brother Ren wants to join our biyunzong. It''s what he wants." Xie Tianji patted his chest.


    Yang Xuan sighed. He had no choice but to do this. If he didn''t want this guest Qing token, it''s still unknown whether Wudao could let him leave. You know, he still has to dig a spirit stone. He must not stay in Biyun sect.


    Xie Tianji called a man. After arranging a few words, the man turned and left.


    Not long after, Ling Wudao came in, handed a cyan token to Yang Xuan, smiled and said, "elder Ren, welcome to join my Biyun sect."


    Yang Xuan smiled, put away the token and didn''t speak.


    Ling Wudao continued to laugh and said, "elder Ren, this token you hold is the highest identity of elder Keqing. You have many rights, which shows the sincerity of our Biyun sect. I hope elder Ren will not disappoint our Biyun sect."


    This was already a warning. How could Yang Xuan not hear it? He nodded to Ling Wudao and said nothing.


    The whirlpool between Biyun sect and Juling sect. He doesn''t want to fall into it. He just wants to dig out the spirit stone and fly away.


    With this token of biyunzong, he can act more conveniently.


    Of course, he knew that Biyun Zong could accept his request because of his knowledge of mathematics and Xie Tianji''s face. He secretly investigated him for a long time, and maybe even his identity would be revealed when. This is also the reason why he wanted to be an elder guest Qing.


    Xie Tianji was impatient and said, "brother Ren, now you can talk about the method of measuring the straightness of the week."


    Hearing the speech, Wudao also showed an expression of listening.


    Yang Xuan was not wordy either. He spoke directly and explained the relevant knowledge of PI for the two people. Of course, he kept an eye on it and didn''t explain it too carefully. Even the PI was only accurate to two decimal places, just like what he told Qingxue royal family.


    He had a hunch that the hand he was likely to leave would bring him unexpected gains.


    Xie Tianji can''t wait to check the calculation on the ground. Yang Xuan finds that the bluestone ground has long been covered with all kinds of messy graffiti. It seems that Xie Tianji usually has the problem of squatting on the ground to check the calculation.


    No way sighed at Yang Xuan. Although he was not as professional as Xie Tianji in mathematics, he also understood Yang Xuan''s explanation.


    He couldn''t help admiring Yang Xuan.


    After checking for a long time, Xie Tianji suddenly patted his thigh and stood up. He suddenly rushed to Yang Xuan, grabbed his hand and said excitedly, "how did you find this? Genius, it''s genius."


    Yang Xuan thought: the primary school math teacher taught me.


    But of course he couldn''t really say that. He just smiled and pretended to be mysterious.


    A few days later, when Yang Xuan was about to leave Biyun sect, Xie Tianji sent a disciple gift to Yang Xuan.


    From the initial disdain to the final respect for heaven and man, in just a few days, Yang Xuan showed a corner of the iceberg in mathematics, which numbed Xie Tianji and Wudao.


    Xie Tianji, in particular, boasts that he studies heaven and man together with mathematics. No one in the world can compare with Yang Xuan, which is a joke.


    Any question he raised can always be answered in the fastest and most correct way in Yang Xuan''s hands. It seems that there are no problems that can embarrass him in the world.


    In the end, Xie Tianji simply couldn''t understand what Yang Xuan was saying.


    What AIX, what tile aunt, what scatter eagle, can scatter eagle, all listen to him confused, relaxed and happy.


    He sometimes felt that Yang Xuan was talking nonsense, but Yang Xuan could always answer any questions with these bird language he didn''t understand, and he couldn''t help but believe it.


    Even, he once heard a sentence from Yang Xuan''s mouth: Chicken changes lotus root unchanged, Fu


    At that time, Yang Xuan only said half and then shut up. Xie Tianji keenly felt that there seemed to be a big secret in Yang Xuan''s words.


    What is the relationship between chicken and lotus root? Xie Tianji wants to break his head.


    The middle-aged man who said that Yang Xuan couldn''t afford to pay for it that day had already fallen to the ground in admiration of Yang Xuan, so he had to kneel on the ground and call the master.


    The reason is that once Yang Xuan accidentally saw him doing an experiment, so he casually pointed out a few words, solved a big problem of Xie Tianji, and surprised the disciple directly. After that, he never dared to do it in front of Yang Xuan again.


    After listening to Tao for a long time, he retreated and left, because he couldn''t understand what Yang Xuan said in only a long time.


    Before he left, he was always thinking about a question: what is the decomposition quality factor?


    He had a hunch that if he could understand this sentence, he would make a qualitative leap in mathematics.


    When Yang Xuan left, Xie Tianji and Ling Wudao went directly to the outside of Biyun sect. The other disciples of Biyun sect were stunned. They were inexplicably respectful to Yang Xuan. At the same time, they also kept Yang Xuan''s appearance in mind and listed it as an object that should not be offended.


    Can they offend the two giants of biyunzong.


    "Brother Ren, you must go early and return early!"


    In Xie Tianji''s reluctant eyes like looking at his wife, Yang Xuan answered and quickly slipped away. At the same time, he also secretly wiped the cold sweat on his head.


    Go on, he won''t know what to say.


    It''s not that he won''t, but that no matter how profound things are, they can''t be understood in the language of the world.


    In the end, he simply told Xie Tianji some concepts of unknowns.


    Up to the second grade of junior high school.


    Yang Xuanyin thought to himself that at this time, he just knew that it was difficult to be a teacher. Sometimes, looking at Xie Tianji''s incomprehensible appearance, he wanted to slap him.


    Shaking his head, Yang Xuan threw out the strange idea of hating iron but not steel, recognized the direction of Qingxue city and flew over.


    Bandit Shuai is still there waiting for him to continue his great cause of digging ancestral graves.