The classroom was very quiet, with only the "rustling" sound of the pen sliding on the test paper.

In order to take care of the six children who were taking the exam, Ma Zhongguo deliberately stopped giving lectures and took four elementary school students from his side to study quietly.

Lin Ping watched the six children answer the questions on the podium. He frowned and bit his nose, and seemed to have encountered difficulties. He then stretched his eyebrows and smiled happily, and it seemed that he was finding the idea to understand the questions.

Lin Ping looked at the children and was stunned, and then smiled foolishly. The children in his youth were so simple and cute. Their joys, angers, sorrows and happiness were written on their faces, and you could tell at a glance whether they were happy or angry, sad or happy. You don’t need to figure out their thoughts at all, their thoughts were written on their faces.

And what about adults?

An important sign of maturity is "happiness and anger are not reflected in colors", which means that a person is calm and well-educated, and his feelings are not exposed. That is to say, mature people cannot let others see your emotional color towards something when doing things.

Many people say that this is not hypocrisy, it is called disguise.

Disguise is to survive better in the adult world. Disguise yourself as a smile to please others, and disguise yourself as a strong person who will not cry.

If you are good at disguise, you will be very tired; if you are not good at disguise, you will be very difficult.

In the adult world at the age of 18, there is no word "easy", but it is not necessarily the case. For example: it is easy to be obese, easily bald, and suddenly die.

Exercise more and stay up late less.

"Teacher!" Liu Xiangqian suddenly raised his hand, "Is this question wrong?"

Lin Ping smiled and walked over to pick up the test paper and looked at it carefully, then returned it to Liu Xiangqian: "There is no error in the question, please think about it carefully."

Lin Ping wrote this test paper according to the principle of "6+2+2", that is, 60% of basic simple questions, 20% of elevated questions, and 20% of Olympiad mathematics questions.

Lin Ping felt that Liu Xiangqian and the five junior high school students had no problems with 60% basic simple questions and 20% high-end questions. They could easily get these 80 points with a careful mind, while 20% of the Olympiad questions would be difficult.

These 20% of the Olympiad questions were carefully selected by Lin Ping. There are slightly simpler elementary school Olympiad mathematics chicken and rabbit cage, water inlet and drainage, and slightly more difficult proof questions. There is even the famous "Gauss 5050", which is the question from 1 to 100. This question is put as the final question to the last question. If these students cannot find a good solution to this question, they can only start from 1+2, +3, +4... and all the way to 100, but this is a time-consuming thing.

"Note that this exam time is 90 minutes, and an hour has passed now." Lin Ping reminded.

At this time, everyone also achieved the last 20% of the questions, and they all frowned. Only Wang Yige was different. According to Lin Ping's observation, he completed the previous simple questions and elevated questions twenty minutes ago, and entered the stage of conquering the mathematics questions early.

"The final question is a very, very difficult question, with low scores. The teacher specially asked you to test your mathematical thinking. If you feel that time is limited, you can choose a feeling question for thinking."

Lin Ping was afraid that the question would make students doubt their lives because he was afraid that it would be too difficult, so he advised them with kind words.

"Teacher!" Liu Xiangqian raised his hand again.

"What's wrong?"

Liu Xiangqian stood up and held the test paper and said, "A swimming pool has a water inlet pipe and a water outlet pipe. It takes 4 hours to fill all the water, and 5 hours to put all the water in. First, turn on the water inlet pipe. When the water in the pool accounts for one-quarter of the pool, then open the water inlet pipe and the water outlet pipe at the same time. Ask how long it takes to get the pool to two-thirds full?"

"What's wrong?" Lin Ping asked.

"What a good swimming pool, you put water in while putting water in. Isn't this a disease?" Liu Xiangqian scratched his head and said, "This is a waste of water resources, teacher."

Lin Ping smiled and asked Liu Xiangqian to sit down, and then said: "Students should understand that mathematical problems do not equal real problems. Mathematical problems are mostly theoretical assumptions. Assuming a situation will be put into tests of your mathematical thinking. After you master it, you can transform it into real problems and use them to solve real problems."

In the past, Lin Ping also felt that the question-making person who had such problems had a toxic brain and was not in line with the reality of life at all. It was not until Lin Ping had a mobile phone that he was playing with his mobile phone while charging and found that everyone would really do stupid things like "water coming out and water".

It is much wiser to compare the problem of "water out and water inlet" to the problem of "charging and electricity use". For example, you have 23% of your phone's battery left, which is only enough for two and a half hours. So you decide to charge your phone and play while charging. The charging speed is known to be 15% per hour. Assuming that the power consumption speed and charging speed are always at an average speed throughout the entire process, how long does it take to fully charge while charging?

It's much more realistic if you look at this problem.

"There are 15 minutes left before the end of the exam." Lin Ping looked at the watch and reminded.

"Teacher, I'm done."

At this time, Wang Yige stood up from his seat and handed the test paper to Lin Ping.

The other five children looked at Wang Yige and looked incredible.

"Show me, let me see if he has some questions." Liu Xiangqian said with a head protruding.

"Be your own, you've really finished it and you've written it all."

As he said that, Lin Ping showed the test paper a little.

"Hmph, I'm confused, I must be writing nonsense." Liu Xiangqian muttered dissatisfied.

Lin Ping took a general look at the test paper and was surprised. Not to mention right or wrong, Wang Yige actually did all the questions. Lin Ping quickly turned to the last question, which was the widely circulated question from 1 to 100 that the famous mathematician Gauss did in elementary school.

Now Wang Yige's answer to the test paper is: 5050.

That's the answer to this question.

Lin Ping couldn't help but ask excitedly: "How did you get the answer to this question in such a short time?"

At this time, Liu Qingmei, who was standing by, also got this question, but she was using the stupidest method, starting from 1 to 100 one by one.

Wang Yige actually got the answer to this question quickly and correctly. Isn’t that a contemporary Gauss!

The future is promising!

"Uh..." Wang Yige scratched his head and said honestly: "Teacher, I actually saw this question in the storybook my father bought for me. Then when I saw it exactly the same, I wrote the answer on it..."

Lin Yiping also scratched his head speechlessly, okay, I was so excited.

"Do you know the method of this question?" Lin Ping asked again.

Wang Yige nodded: "Well, I know that from 1 to 100, it can be regarded as 0 to 100, so 0+100=100, 1+99=100, according to this rule, that is, 100 divided by 2, there are 50 100 sums, and there is still an intermediate number 50. So it is 50x100+50, which is equal to 5050."
Chapter completed!