Rebirth of the Rich Second Generation's Growth Diary

Chapter 26 Advancement
Li Xu didn't memorize any English words today, and Ye Ling still felt a little uncomfortable with it.

When she came back, she saw Li Xu writing and drawing seriously on a newspaper. Out of curiosity, she leaned over to take a look.

"Hey, this is..."

Ye Ling took a careful look and found that it was a mathematics knowledge newspaper. She then looked down at Li Xu and saw that he was frowning with a serious expression.

Ye Ling bent down and took a careful look.

At this time, Li Xu was reading a question in the newspaper, which was to find the remainder when 7^222 was divided by 10.

The corners of Ye Ling's mouth twitched slightly... Although she could also go to a 985 university, it didn't mean that she was good at math.

Mathematics was her biggest weakness during the college entrance examination. She only scored around 120 points. This score showed that her grasp of mathematics was only basic.

As for the question that Li Xu was looking at now, she could tell at a glance that it was completely beyond the syllabus.

This problem definitely cannot be solved by brute force... 7 to the power of 222 is probably too much to display on a calculator.

So how should this problem be solved?

No, this is a junior high school question?

Junior high school textbooks generally do not explicitly mention Euler's theorem in fields such as number theory and graph theory. Only Euler's theorem on polyhedrons appears in some versions of junior high school mathematics textbooks.

This problem requires the use of the foundation of Euler's theorem... the knowledge point of congruence.

But even if you don’t master it, it basically won’t affect your normal academic advancement.

When Ye Ling took the college entrance examination, she didn’t even know that there was such a thing as a competition to get into college.

She couldn't help but ask, "Is this a junior high school math problem?"

Li Xu's train of thought was interrupted. He put down his pen and looked up at his cousin Ye Ling: "This question is a simple example from a junior high school math competition."

Ye Ling frowned and touched her chin, a little surprised: "You are starting to do such difficult questions now?"

Li Xu shook his head and said, "Actually, this question is not difficult. It's a question about congruence."

The question was not difficult, but he was confused about how to explain the concept and properties of congruence to Xia Xiaomiao... In fact, he himself was also in a state of confusion.

Ye Ling's expression turned a little confused: "Ah, the same remainder?"

How come I haven’t heard of…

Then Li Xu lowered his head and solved the problem in no time.

"Cousin, you see, first of all, because..."

"And because..."

Ye Ling had not been exposed to mathematics for a long time. In her ears, what Li Xu said was roughly equivalent to...blah blah blah blah, and finally came to a conclusion: Therefore, the remainder is 9.

Ye Ling smiled and patted Li Xu on the shoulder: "Well, that's great!"

Li Xu raised his head, blinked and asked, "Do you understand?"

Ye Ling was stunned and stammered, "Well, I think I understand..."

It would be so embarrassing to say that you didn’t understand.

Li Xu touched his chin and thought for a moment.

To be honest, he himself was still confused about the congruence theorem. At this time, the difficulty lay in how to explain the concept of congruence to Xia Xiaomiao.

Seeing that my cousin seemed to have understood, I continued, "Then, cousin, do you understand Euler's theorem?"

What is Euler's theorem? I've never heard of it.

Ye Ling's expression suddenly became a little awkward, and she said with a stiff upper lip, "Well, this... I don't quite understand, but you just said that this formula can solve this problem, so I understand."

Isn’t it just a formula? At this time, even if you don’t understand it, you have to insist that you understand it.

Li Xu pulled his cousin Ye Ling to sit down and said, "Cousin, let's strike while the iron is hot. I'll tell you more about the properties of congruence."

“Only when you can truly deduce it can you be said to have truly mastered the concept of congruence.”

"Uh, why should I strike while the iron is hot with you?"

The corner of Ye Ling's mouth twitched slightly, and her brain was spinning rapidly, thinking about how to escape.

However, Li Xu, who was so angry at this time, did not even observe Ye Ling's expression and started talking to himself.

"Let's first look at how congruence is described... Let m be a positive integer. If two integers a and b satisfy..."

"We'll take it one step at a time."

When Li Xu was talking to Ye Ling, his brain was also working rapidly, thinking about how to make Ye Ling understand.

"First, let's look at this formula..."

"Cousin, do you think there's any problem getting here?" "Uh..." Ye Ling's brain froze for a moment.

Li Xu, immersed in it, glanced at his cousin and said, "Don't you understand? Let me explain it in more detail... To put it simply, if two different positive integers are divided by the same number and get the same remainder, then these two numbers are congruent modulo that same number..."

Li Xu tried to describe it in his own words so that Ye Ling could understand.

"Uh……"

Ye Ling's mind was in a mess. She couldn't help but look at Li Xu who was lecturing enthusiastically, but she didn't hear a word he said.

what's going on……

Why did Li Xu inexplicably start teaching her?
As if noticing Ye Ling's distraction, Li Xu tapped the example question on the newspaper with his finger, and his tone became a little stern: "Do you understand?"

Ye Ling was surprised and replied subconsciously: "Yeah, I understand..."

Then he immediately came to his senses, slammed the table and stood up, "Li Xu!"

Li Xu finally came out of his lecture state, coughed, touched his nose, and then said in a very unimpressive manner: "If you don't want to learn, then don't learn. Why are you so fierce..."

It wasn't completely fruitless. At least when I was explaining the problem to Ye Ling, I further deepened my understanding of some key contents of congruence.

Especially when he can explain those concepts in his own plain words, it shows that he has truly mastered the meaning of the concepts.

There were some unclear points before, but as I was talking and thinking about it, it all became clear now.

The reason why he did this with such great care was naturally to make Xia Xiaomiao understand.

Just now, he himself didn't quite understand what a model was, let alone explain it clearly to Xia Xiaomiao.

Ye Ling realized her attitude wasn't very good, and sat down again, somewhat annoyed. "Why are you studying this competition question already?"

Li Xu hadn't told Ye Ling about his teaching of Xia Xiaomiao. He laughed it off and said, "I just wanted to challenge myself... Do you have any high school textbooks? I already have a solid grasp of junior high math."

Ye Ling stood up and said, "Then you can challenge yourself slowly. I'll leave first and go to the cafeteria to get some food."

"Don't leave in a hurry, discuss it with me..."

Ye Ling quickly quickened her pace.

……

Xia Xiaohe carefully divided the headache powder into half, poured it into the water, and handed it to Xia Xiaomiao.

My brother's headache started coming back again.

Xia Xiaomiao shook her head and said, "Sister, I don't want to drink. I'll just wait until Brother Li Xu comes."

"what?"

Xia Xiaohe didn't understand for a moment what Li Xu's coming over had to do with his brother's headache.

Xia Xiaomiao said, "My headache went away after Brother Li Xu taught me some new knowledge."

Xia Xiaohe blinked, looking a little confused.

In fact, recently, she gradually realized that when Li Xu taught mathematics to her brother, it was not the one-sided imparting of knowledge as she had initially thought.

Xia Xiaohe's schoolwork was very heavy. Like most people, she thought that there was no need to teach her brother math knowledge beyond the syllabus. So for a long time, she had no idea about her brother's learning progress.

Li Xu was explaining mathematics to her brother, but in her heart, she was looking at the matter from another perspective...

Her younger brother really didn't have any friends, and sometimes he could even be described as a loner, which made her a little worried.

The younger brother likes Li Xu very much, and Li Xu is very patient, or perhaps Li Xu also likes his younger brother very much. When the two of them get along, the younger brother doesn't feel so lonely.

Xia Xiaohe did not pay attention to their progress in the course.

But as the knowledge content entered the third-year junior high school textbooks, the situation gradually changed.

At first, the younger brother just had some doubts and said, "Brother Li Xu's grades are probably not very good, right?"
Later, this doubt seemed to have substantial evidence. When someone evaluated in front of me, I felt that Brother Li Xu’s lectures were not that clear... He seemed a little bit stupid.

Xia Xiaohe was about to criticize her brother seriously, but she didn't expect his next sentence, which was said in a serious tone, to choke her.

"But generally speaking, my sister is still dumber."

At this time, Xia Xiaohe put down the cup and asked curiously: "If you think Brother Li Xu is stupid, then why did you ask him to explain the problem to you?"

Xia Xiaomiao thought about it seriously and said, "I don't know why, but he seems to understand me as he talks... Well, actually, there are some things I understand, but I also say I don't understand. I'm worried that if I understand everything, he won't come to teach me in the future. I think he's a good person. He brings me a lot of snacks and listens to me carefully... Oh, sister."

Xia Xiaomiao raised her head and said to Xia Xiaohe, "Or, why don't you let Brother Li Xu be your boyfriend?"

In this way, Brother Li Xu can keep explaining the questions to him.

Xia Xiaohe was silent for a moment, then beat Xia Xiaomiao.

(End of this chapter)