Ni'er was holding a stack of paper under her hands, with dense numerical calculations on it. The little girl was still writing.

"Little girl, what are you?" Jiang Xingchen stepped forward and sat beside Ni'er and asked.

"Ah!" Ni'er exclaimed, and then she discovered Jiang Xingchen: "Sir, why are you here... I found some problems!"

"Oh? What problem did you find? The calculation volume needs to be so large?" Jiang Xingchen asked curiously, picking up the stack of paper under Nier and watching it carefully.

"I found something strange! If it is an isosceles right triangle, according to the Pythagorean theorem, the length of the oblique edge will be a strange value!" said Nier.

Jiang Xingchen also saw Ni'er's calculation clearly at this moment. She was digging squared, but what she digging was infinite and non-cyclic decimal.

"No need to forget it, this is an irrational number!" Jiang Xingchen put down the draft in his hand. He had indeed not mentioned the irrational number before, because he didn't know how to explain it. He just vaguely remembered that using rational number division can be defined, but he had only heard of rational number division and had no idea what was going on.

"Unreasonable number?" Ni'er frowned even more, and then asked, "Is this irrational number meaningless? But it is obviously a hypotenuse. ●︽ has practical significance. A line segment should have specific values, so why is it unreasonable?"

Jiang Xingchen scratched his head. He really couldn't explain this thing. In his previous life, this irrational number triggered a mathematical crisis of more than two thousand years.

After thinking for a while, Jiang Xingchen decided to let the little girl jump out of here first and not be stuck here.

"This is a big problem. With your current mathematical knowledge, it cannot be solved yet! When your future mathematical knowledge is deep enough, let's study this problem!"

But after Jiang Xingchen finished speaking, he knew that his words were in vain. The little girl didn't listen at all and was still frowning and thinking.

"Nier, mathematical deductions always need to be done step by step! There are more problems with graphics than isosceles right triangles... These days, you have been looking at graphics, so I ask you, if you give you a ruler or a compass, can you do all those graphics? "

The little girl raised her head, nodded without thinking, and said, "I can do it all, and I have done it!"

Jiang Xingchen saw that attracted Ni'er's idea and continued, "Okay, let's increase the difficulty now! Let's use a ruler and a compass. Note that this ruler has no scale! Then can you divide any angle into three equal parts, and can you make a square so that its area is equal to the area of ​​a known circle!"

Jiang Xingchen talked about the three major problems of ancient mathematics. But he only remembered two, and he forgot about the problem of cubic product.

Through this study, analytical geometry can be derived and graphical problems can be solved by algebraic methods. Of course, Jiang Xingchen did not want to tell Nier that if Nier could study her own eyes, it would be really amazing.

In addition, he also wanted to let all the children study it together. If he could find someone who is like-minded with Ni'er, it would be even more perfect. In the previous life, the formation of a mathematical system was definitely not something that one or two people could do. Although he had such a plug-in in this life, it would be quite difficult to rely solely on Ni'er himself.

"Okay! I'll try to solve these two questions first!" Ni'er was very interested in doing the questions and nodded to Jiang Xingchen with a smile.

"Little girl, do you think the question I asked is very simple?" Jiang Xingchen patted Ni'er's head.

"Looking...it doesn't seem difficult!" Ni'er said.

"Okay! Then you can try it out!" Jiang Xingchen said as he stood up, and saw a stack of draft paper made by Ni'er at first glance, and a sudden flash of inspiration in his mind.

"Study hard, I will give you a gift!" Jiang Xingchen said.

"Ah? Sir, are you going to give me a gift? What... is it a delicious meal?" Nier asked happily.

"Small foodie! If you really solve these two problems, I will make you a big meal!" Jiang Xingchen raised his hand and scraped the little girl's nose.

"What the Lord said is not allowed to repent!"

"I will never regret it, but the gift I give you is not something to eat! You will know when you look back!" Jiang Xingchen said, waved his hand and walked towards the inner room.

Ni'er happily said goodbye to the Lord, and then lowered her head to study the two graphic questions...

When she entered the laboratory, Xian Ning was also writing and drawing at her desk. She could see that she was very involved and did not respond to Jiang Xingchen's arrival.

"Xian Ning, how are you doing research?" Jiang Xingchen asked.

"You are here!" Xianning raised his head, put down the pen in his hand, and sighed: "There are too many parts for steam locomotives, and the boiler needs to be horizontal to increase the heating area! It also needs to increase the number of cylinders and connect more wheels... There is another main problem, which is brakes!"

Jiang Xingchen shook his head helplessly, and he didn't know the braking system of the steam locomotive. He could only study this little by little.

"Xingchen, your place is not easy either. You have to hold on to the molds and lathes!" Xianning said.

"I know this. This is just the beginning. I will have to train maintenance workers in the future. A railway requires a lot of people to maintain... Okay, you can study it first! I'm back!"

Jiang Xingchen turned his head and took two steps, suddenly stopped, and said, "By the way, I have something for you to come back, I thought of when I was guiding Ni'er just now!"

"What?" Xian Ning asked.

"I'll tell you when I make it. This thing will take a while to learn it!" Jiang Xingchen said with a smile.

"I have to learn for a while, so I'll talk about it when I'm working on a steam locomotive. I really don't have time now... and the flat glass has not been made yet... The construction on the ground has begun in Duanjia New Town, but you have to install glass windows!"

Jiang Xingchen smiled bitterly. When he was building a new city, he thought about getting closer and installing glass windows! But now there is no progress in flat glass! The main reason is that tin has not been found, so floating production cannot be carried out.

"That's nothing to do. What should we do if we can't be busy now!" Jiang Xingchen sighed. There were still too few talents in the territory. Thinking about the construction of the new city and the building was covered with paper windows, he felt like he was struck by lightning.

"Let's take a look after the university is completed and students will be recruited to the public. I hope there will be good seedlings." Jiang Xingchen sighed.

"Xingchen, I just talked about cars and glass, and I forgot to do the serious business!" Xianning put down the pen in his hand, stood up, and asked, "Can the magnifying glass you designed be larger?"

"This... should be OK! But it requires a lot of attempts, we don't have time now!" Jiang Xingchen replied. If Xianning said telescopes, this is a little simpler. But the microscope is different. Although they all have two groups of convex lenses, the microscope is much more refined and requires multiple experiments.

"Don't worry, just remember this... You can really do it. How did you figure it out by magnifying glass?" Xian Ning asked with a smile.

"Haha, you don't know me yet, maybe a strange idea will come up at any time!" Jiang Xingchen said casually, turned around and ran away.

Xianning shook her head: "Every time I ask this question, I run away..."

Back at the lord's mansion, Jiang Xingchen immediately ordered his subordinates to find wood and start making it with a carved knife. In no time, a rectangular frame came out, and then drilled holes to make beads...

What Jiang Xingchen made was abacus. The calculation tools he had been using from ancient times to the present in his previous life. Even when modern electronic products were flying all over the sky, they were still useful. He thought of it only after reading Ni'er's stack of calculation drafts.

With the abacus, it is faster to calculate the four calculations. In the last life, it was said that masters were faster than calculators.

With this abacus, it is much faster in financial accounting, which is definitely a super blessing for Grandpa Fu.

Jiang Xingchen’s idea was to push the abacus into the classroom, with more than a thousand children. Different talents, different personalities, and different preferences, it is impossible for them to enter the research institute. They will definitely enter various positions in the future. After learning abacus, it is equivalent to cultivating talents for the financial department in the future.

"Boy, what are you doing?" When Jiang Xingchen was busy, the old man came to the yard.

"It's fun!" Jiang Xingchen turned his head, smiled at the old man, and said, "Do you want to try it?"

"No!" The old man tried his best and said loudly: "You kid want to be fooled again, right? You didn't think about it when you smiled!"

"Tsk!" Jiang Xingchen curled his lips and said contemptuously: "You want this thing, I'm giving it to you! And I think you can still use this, Kong Ming Lock is enough!"

"You're going to cause trouble! The Kongming Lock has been unlocked, and you still want to stump me!" The old man smiled proudly, as if he saw Zhao Danqing and the second child sweating again.

"Hmph! That's why you're called untied? Don't put gilds on your face. Let me tell you that there are more types of Kongming Locks, and there are all kinds of them. I only gave you twenty-four ones that day. If you want to try it, I'll make you for forty-eight ones in the future!"

The old man's muscles trembled violently, and a black line fell, but he didn't want to suffer that kind of torture anymore.

Jiang Xingchen continued: "In addition to Kongming Lock, I have more fun and more difficult things! Call it Rubik's Cube. If you are interested, I will make you a fifth-level one for you, which will definitely make you happy!"

"Forget it, forget it!" The old man waved his hand quickly and said, "I'll talk about these things you said when I want to be purified for a while!"

Jiang Xingchen smiled and asked, "Didn't you learn Tai Chi from Miss Tang? Why did you have time to run out? Haven't you heard of Tai Chi for ten years and never go out? You are so unconscious, and Miss Tang doesn't care about you?"

Jiang Xingchen scolded him, and surprisingly the old man did not refute, but his eyes shrank, showed a bitter smile, and sighed: "Boy, don't mention it! I'm afraid I can't learn this Tai Chi..." (To be continued, please search for Astronomy, the novel is better and faster!

ps:  The third update is over!
Chapter completed!