The sun is rising in the east and the weather is clear. It looks like it is a good day today.
At 7:50 in the morning, Yu Hua, who had just finished his morning exercise, was sitting in his seat, holding a pen in his right hand and chewing on a hard multi-grain steamed bun in his left hand. He stared at the table and opened the arithmetic book on probability and statistics, using the ten minutes before class to study.
Yesterday I mastered the small principles of counting probability, and I have just reached the stage of permutations and combinations.
Definition of arrangement:
Randomly select m (m≤n, m and n are natural numbers) elements from n different elements and arrange them in a column in a certain order.
Definition of combination:
Randomly select m (m≤n) elements from n different elements and combine them into a group.
The difference between the two is that arrangement is related to the order of elements, while combination has nothing to do with the order of elements.
"Permutation means to remove M elements from N elements to do the work. Arrangement means to extract M elements from the N elements to do the work and study. The former has the same purpose, while the latter has different purposes. It's good. Hey, what do I want?
Let's use dry rice as an example..." Yu Hua took a bite of a dry multigrain steamed bun. It wasn't very tasty when it was cold, but it was better than filling his stomach. Looking at the definitions and judgments of permutations and combinations, he quickly understood its meaning.
I have to say that a meal without oil and water is really not filling. The staple food for breakfast is multi-grain steamed buns and steamed buns, which are the same as last night's dinner. The side dishes are pickles and pickled Chinese cabbage.
In short, there is no oil or water at all.
Last night, Yu Hua woke up from hunger once after sleeping until midnight.
After finishing breakfast today, Yu Hua was careful and ordered an extra steamed bun. Then, led by the school's physical education teacher, he went for morning exercises to exercise like the students of later generations.
After finishing the run, Yu Hua just sat down when his stomach began to growl, so he quickly took out the leftover steamed buns from this morning to satisfy his hunger.
"Here, Yu Hua, here you go, something good." Zhou Yuan, who had just sat down, saw Yu Hua nibbling cold steamed buns. He then took out a love iron box with exquisite light red packaging from the drawer, opened the lid, and took out
Two golden long objects were shouted at Yu Hua and handed over.
Hearing Zhou Yuan's shout, Yu Hua raised his head, a little confused, and looked at two things that looked like small yellow croakers: "This is it?"
"You'll know when you open it." Zhou Yuan smiled.
Putting the steamed bun in his mouth and biting it, Yu Hua freed up his left hand and took the two items handed over by Zhou Yuan. They weighed about two taels. He picked up one of them and peeled off the golden wrapping paper. Inside was a piece of black chocolate.
"My dear fairy, chocolate?"
Yu Hua's eyes widened immediately, and he subconsciously took out the steamed bun in his mouth with his right hand. It was not that he had never seen the world, but that the thing in his hand was too rare.
As for the price?
As an imported product from the West, chocolate belongs to the ranks of imported foods. It is a high-end food that belongs to the aristocracy. A box of 500 grams of chocolate costs at least ten yuan.
Even though this thing is expensive, the most important thing is that it is impossible to buy.
Sensing Japan's ambition to invade, the Nationalist Government listed sugar as one of its strategic materials. Sugar was no longer available in major cities across the country, let alone chocolate that was higher than sugar.
The two pieces of chocolate in my hand, which are about two taels each, cost at least five oceans.
Darling, this tablemate Zhou Yuan comes from a wealthy family. He can just buy two pieces of chocolate at random.
Zhou Yuan said with a smile: "Classmate Yu Hua is very knowledgeable. This is American Hershey's chocolate. My sister brought it to me when she came back from the United States this year. Please try it."
"Okay, if that's the case, then I'm not welcome."
When Yu Hua heard Zhou Yuan's words, he didn't show any pretense and just stuffed it into his mouth. It tasted mellow and slightly bitter, both sweet and bitter, and contained a high amount of calories.
If you compare calories, these two pieces of chocolate in your hand can beat the half-eaten steamed buns by ten blocks.
"How does it taste?" Zhou Yuan asked with concern when he saw how delicious Yu Hua's food was.
Yu Hua ate the chocolate and took advantage of the chewing time: "It's a bit bitter, but it's very fragrant. Aren't you hungry?"
"No, I don't like the bitter taste in it. Just get used to it. I'm going to read a book." Zhou Yuan shook his head. Although he knew that chocolate is a good thing, he just couldn't get used to eating this foreign thing. Seeing Yu Hua eating happily
, then turned back to read the book.
After finishing the piece of chocolate in a few seconds, the hunger in his abdomen disappeared instantly. Yu Hua finished the remaining half of the steamed bun, looked at the remaining piece of chocolate, and put it directly into the drawer to eat next time he is hungry.
.
After putting away the chocolate, he raised his head and glanced at Zhou Yuan who was concentrating on his studies. Yu Hua silently wrote down his feelings for the chocolate. Giving it to you is a sign of friendship, but not giving it to you is a duty.
Now that you have eaten it, you have to remember that no matter whether others care or not, they need your affection or not.
Not hungry, and with high-calorie chocolate as an energy supplement, Yu Hua started reading again. His mind was clear and thorough, and his understanding was very fast. His reading efficiency was suddenly much higher than when he was hungry, and he was quickly immersed in it.
Today is the eighth day of the first lunar month, Thursday.
According to the curriculum set by the school, eight classes are required every day, four classes in the morning, four classes in the afternoon, and self-study in the evening from 7:30 to 10 p.m.
The first class in the morning is arithmetic, taught by Mr. Ren.
"Boom! Boom! Boom!" As the time came to eight o'clock, the school's low and distant bell rang, penetrating throughout the school, reminding the class that it was time.
"Huh... Fortunately, I'm almost finished learning permutations and combinations. Probability and statistics are difficult to say or not. It's easy to do as long as you master the principles of addition and multiplication." Yu Hua heard the bell, came back to his senses, and looked
I glanced at my book and thought to myself silently.
Outside the classroom door, two figures appeared, one was Mr. Luo Wenguang, a senior class teacher, and the other was a strange young man dressed in Western clothes, wearing glasses and looking full of energy.
"The teacher is here." Li Fan, the squad leader, shouted immediately when he saw his successor.
All the students in Neo-Confucianism Class 1 immediately put down everything they were doing, sat down properly, and showed respect.
Immediately afterwards, Luo Wenguang, Mr. Ren, was in front, and a strange young man in a suit was behind. They entered the classroom one after another and walked onto the podium.
"What the fuck?!" Among the crowd, Yu Hua looked at the young man behind Mr. Successor who was walking unsteadily. He was stunned, confused, and almost cursed.
This young man is none other than Hua Luogeng whom I met eight days ago!
Isn’t Hua Luogeng in Tsinghua University? Why did he come to Peking No. 4 Middle School?
What's going on?
No one answered the question in Yu Hua's mind.
"Stand up." Squad leader Li Fan shouted immediately after Luo Wenguang and Hua Luogeng walked onto the podium.
Immediately afterwards, all students stood up, facing the two people, and their bodies were straight.
"Respect the teacher."
"Hello, sir."
Yu Hua and a group of students bowed to Mr. Ren and Hua Luogeng, saying greetings to show their respect.
"Well done, please sit down."
Mr. Luo Wenguang, the senior class teacher, nodded in response, arranged for everyone to sit down, looked around, and said: "Today, the first lesson of the semester, the school specially invited Mr. Hua Luogeng, a professor of the Department of Mathematics at National Tsinghua University, to teach the students. This is the first time for you.
Opportunities must be cherished, monitors must strictly discipline them, students must take them seriously and keep quiet.”