[Chapter 42: The end of the prime number labyrinth]

The course "Prime Number Labyrinth" in the School of Mathematics has allowed the four people in the research group to get up to 585 points, which is higher than the previous "Cardiovascular Ward" points, and with so many points, they only Took an hour and a half!

Remembering the five-day thrilling experience of finding a murderer and fighting monsters in "Cardiovascular Ward", this time got 585 points in one and a half hours, it was really easy.

Yue Xingwen was excited, turned around and gave Jiang Pingce a hug: "Full score? You are so awesome! The three of us are just running errands, and we can get 585 points? It's really comfortable! "

Liu Zhaoqing said with emotion: "This should be the easiest time for us to get points, right? There is a scholar in the team, and it seems like a cheater."

Ke Shaobin also said seriously: "Even if I take a calculator, I guess it won't be as fast as Pingce's mental arithmetic."

Yue Xingwen has always known that Jiang Pingce is very good at mathematics. In high school, Jiang Pingce got full marks in every exam. It is said that the math teacher in their class will directly take Jiang Pingce's paper as the standard answer to give a question.

When he got to university, Jiang Pingce was even more powerful. This time the maze combines math-operation and three-dimensional geometry analysis. road.

Yue Xingwen patted Jiang Pingce's shoulder lightly, and said with a smile, "Great hero, you have worked hard for you this time."

Jiang Pingce said: "It's okay, it's not hard."

After taking the first course, the time in the library is ten o'clock in the morning, Yue Xingwen glanced at the clock on the wall and said, "Let's go back to the dormitory first, Brother Zhuo Feng and the others are going to retake the courses of the medical school. , it should be out soon."

When the four of them went out, they returned to the hall of the School of Mathematics. Many students gathered under the big screen of the class schedule. All the students were frowning, apparently not knowing how the School of Mathematics should pass the test.

Yue Xingwen glanced at the bewildered classmates, lowered his head and thought for a while, put his head close to Jiang Pingce's ear, and said softly: "The mathematics school's "Prime Number Labyrinth" class has a high failure rate. 65. It seems that many students are stumped. If you don't mind, why don't you share our customs clearance strategy with everyone and help them?"

Jiang Pingce simply agreed: "Okay, I'll go back and sort out my thoughts."

They have already passed the exam, and sharing the strategy with the students behind will not have any impact on their own grades, just like many senior classmates in the university will share their experience with junior classmates and junior classmates. , provide the same review materials.

Yue Xingwen has been helped by many brothers and sisters in school, and he himself often shares information on the forum.

Jiang Pingce never did this. But nowadays, the library is different from reality. If you fail the subject, you will have to rebuild it. If you fail again, you will die! Since Yue Xingwen called for the establishment of a college alliance, Jiang Pingce was of course willing to cooperate with him and share his experience, so that the following students could pass the test more easily.

The two returned to the dormitory, and Jiang Pingce began to organize the maze map.

He redrawn the maps on the upper, middle, and lower floors, took pictures and uploaded them with the tablet that came with the dormitory, and then posted a post on the forum——

[Mathematics College "Prime Number Maze" course clearance strategy]

Jiang Pingce's strategy post is very concise, using the black Song font that comes with the forum. Like a math problem, he simply listed a few points.

1. Don't want to do additional questions, just ask for 60 points? The passing method of the passing team:

The prime number maze is a three-layer three-dimensional structure. After entering the maze, you can ignore all the numbers in the room. You don't need to calculate whether it is a prime number. Simply use the number on the door as the number, and draw a route while walking. You can go straight first. , After encountering a dead end, retreat one room at a time, first right, then left, find the elevator on this floor as quickly as possible, and go up and down the stairs.

The upper and lower layers of the maze are 7x7 with a total of 49 rooms, draw a total of 49 square grids of 7 horizontal and 7 vertical on the paper, go straight to the end in any direction, turn right or left and continue until the end, also That is? Take an "L"-shaped route. At this time, you will be in a corner of room 49, and then follow the "s"-shaped route to check, so that you will not take a repeating path and get lost.

After finding the elevator, go out of the maze, the course is completed, and the grade is ?60.

The detailed three-layer plan of the maze, the synthesized three-dimensional graphics, and the maze route map are attached for reference. In the next exam, there may be some changes in the interior of the maze, and the numbers will definitely change, but the overall structure and clearance ideas will remain the same.

2. Thinking? How to pass the team with additional questions:

The additional problem requires collecting all twin prime numbers, so it is necessary to search all the rooms in the maze and calculate whether each number is a prime number or not. The mantissa 1379 is more likely to be a prime number, and the mantissa 024568 is directly excluded.

1. Quickly determine whether a number is divisible by 3: add each digit of the number, if it is divisible by 3, it can also be divisible by 3. For example, the number 185337 can be directly calculated as 1+8+5+3+3+7=27. If 27 is divisible by 3, then 185337 is also divisible by 3. This number is not a prime number.

2. To quickly judge whether a number is divisible by 7, 11, and 13, you can use the "last three method". Numbers are divisible by 7, 11, and 13.

Example: 939911, can be divided into 939-911=28, 28 can be divisible by 7, then 939911 can also be divisible by 7.

For example; 124371, can be divided into 371-124=247, 247 can be divisible by 13, then itself can be divisible by 13.

The addition method and the last three methods are both? In order to reduce the number of digits and simplify the math-operation.

The proof is as follows:

Let a number be abcdef.

abcdef=abcx1000+def=abcx1001-abc+def=abcx7x13x11-(abc-def)

When abc-def is divisible by 71113, then abcdef is divisible by 71113...

When Yue Xingwen saw this, he gave up thinking with a headache, and slid the following content directly with his fingers.

Mathematics is indeed a magical subject.

The strategy written by Jiang Pingce is serious and rigorous, not only telling everyone what to do, but also "why do you do this".

After Jiang Pingce posted the strategy, the number of replies soared immediately.

Many brothers and sisters majoring in liberal arts left messages one after another: "Xueba, my roommate asked me? Why are you kneeling? Look at your strategy!"

"How do I have confidence to click on the Mathematical Academy's guide? I think? Poke my eyes."

"My eyes tell me it understands, but my brain tells me: it doesn't understand!"

"What do you think about liberal arts students? The courses in the mathematics college are just a pass. You can just read the first one? This senior even drew a map. The first one is still easy to understand. As for the second one. ...I? I just skipped it, sorry."

"That's right upstairs, extra questions? Think too much. Don't do extra questions, just ignore all the numbers, just walk the maze and burn the incense if you can get out!"

Many science students said that after reading the post, their thinking was finally clear.

Classmate Jiang Pingce expressed his gratitude, and many fans, brothers and sisters, confessed to Jiang Pingce in the post.

Mixed in the replies? A lot of "Senior brother is so handsome", "Xueba," "Male god, do you still lack leg pendants".

Yue Xingwen couldn't help but chuckle, looked back at Jiang Pingce, and joked: "As soon as you post this strategy, it is estimated that you will gain a large number of fans in the library, and I will reply to your confession? I have seen it. Dozens of them."

Jiang Pingce said lightly: "If it wasn't for you, I wouldn't have written this strategy."

He was never a kind-hearted person, but he never refused Yue Xingwen's request. He will help whoever Xingwen asks him to help. If Yue Xingwen didn't say anything, he wouldn't spend time actively posting any tips.

Yue Xingwen knew what Jiang Pingce was? This kind of cold and indifferent personality, when he heard this, he laughed? He walked over and sat side by side with Jiang Pingce, and said, "Although there are some people who can't understand your strategy post? , but there are also a large number of students who can learn from it, at least after understanding the first one, they can successfully walk out of the maze and get a passing score of 60.”

He turned his head to look at Jiang Pingce and said softly: "Pingce, writing this guide is just a small effort for you, but it is like a timely rain, which can solve the problem that many research groups cannot get through the prime number maze."

Yue Xingwen's expression was serious: "Don't think I'm nosy and kind. The environment in the library is too cruel. Just now, under the timetable screen in the hall of the School of Mathematics, several girls were crying anxiously. Speaking of the easy-to-follow prime number maze, many students who are not good at math may not sleep well, or even get eliminated. Woolen cloth?"

Every time he talks to people seriously, he can always persuade them.

The corners of Jiang Pingce's lips raised slightly: "Well, listen to you. In the future courses, we can also organize the exam strategies and give them a reference." He looked at Yue Xingwen beside him, and his eyes gradually gradually Become soft, "You always like to help others, the library has it? You are here, and the overall difficulty is much reduced."

Whether it is to formulate a student agreement to restrain everyone and prevent teammates from fighting each other; or to take the initiative to send out strategies to give more reference ideas to the students who will take the exam later...

Yue Xingwen's approach has been helping students.

Yes? He made the atmosphere of the whole library harmonious and warm.

The original dark and thrilling escape game turned into a college final exam of "students work hard together".

From the replies on the forum today, it can be seen that many students responded with light and humorous sentences, and some of them even dared to tease Jiang Pingce in their posts, just like flooding and chatting in the school forum. Compared with the large-scale abuse and quarrels caused by throwing sulfuric acid the day before yesterday, the forum in the library has gradually become more energetic and warm.

Yue Xingwen was too embarrassed to be praised, and said with a light cough: "Don't put a high hat on me, I just do something within my power, this maze is thanks to you. Me? Only now I understand what the map you drew means, it's really amazing, if you let me analyze it by myself, I can't imagine what a 7x7 square is, and I've already become dizzy."

Jiang Pingce said warmly: "My sense of space and computing power are indeed stronger than yours, but your language skills and knowledge are much stronger than mine. Everyone has their own strengths, and it doesn't need to be because of mathematics. Can't compare to me? I'm ashamed."

Yue Xingwen raised his eyebrows: "I? How can I be ashamed? Yes? You are here. When I encounter mathematics in the future, I? Just give up thinking!"

The two smiled at each other.

On the forum, Jiang Pingce's post quickly became popular.

As Yuexing said, this guide post is like a timely rain in the hot summer for the team trapped in the Mathematics Academy on the 2nd floor. If you don't do additional questions, just pass the test, and walk the maze according to Jiang Pingce's method, even if four liberal arts students form a team, they can pass the test with 60 points. Students with strong computing ability can try to do additional questions, and Jiang Pingce listed many skills for them.

There are more and more messages of thanks, and some younger brothers and sisters recognize Jiang Pingce's name and pay homage to Jiang Pingce, the legendary god of mathematics in the Department of Mathematics.

Jiang Pingce glanced at the message and closed the forum.

This is the first time he has shared his experience with other classmates since he grew up.

Three years in high school? Because he was too indifferent, no one dared to borrow notes from him. When he arrived at the university, he was alone and rarely communicated with his classmates except for the occasional self-study with Yue Xingwen.

After the strategy post was posted, and seeing a large number of "thank you" in thousands of replies, Jiang Pingce suddenly felt in a good mood. He used to think that Yue Xingwen loved tossing, but now he found out that only Xingwen, no matter what he faced. Such a world can maintain a kindness and a pure heart.

Such people are the rarest.

Seeing Jiang Pingce keep looking at himself, Yue Xingwen couldn't help but wonder: "What's the matter, am I right?"

Jiang Pingce smiled lightly: "What did you say? Everything is right."

Yue Xingwen patted the other party's shoulder, with a proud expression of "count you wise". After a pause, he said sternly: "Let's not go to the elective courses this afternoon? I'm having a headache looking at the class schedule, so I'll talk about the compulsory courses first."

Jiang Pingce nodded: "Well, I will rest in the dormitory in the afternoon. At 8 o'clock tomorrow morning, there is a compulsory course "Death Code" in the School of Mathematics. Let's go directly to this course."

Yue Xingwen thought about it: "Death code? Listening to the name sounds like a reasoning class?"

Jiang Pingce guessed: "It may be a suspenseful case related to numbers."

The two looked at each other, and Yue Xingwen smiled and said, "If it's a reasoning class, I can still help you. At that time, let's complement each other's arts, science, and thinking, clear customs together, and try to get more points? Upgrade my dictionary!" w, keep in mind:,