Night came, and the shadows of the trees were desolate.

Kong Shucheng bit the apple given by his "mother" and quickly walked out of the Tianjing Garden.

Come to the station.

He gave Lee a call.

Feeling that the situation was a bit serious, Li Luogen asked him to go to Mangshan County tonight.

Kong Shu hung up the phone and immediately got on the No. 193 bus again.

After getting into the car, Kong Shucheng couldn't hold back his excitement and opened the math notebook of Huoyun Xueshen again.

The layman looks at the bustle, and the insider looks at the doorway. The painstaking work of the super scholar in his hand, if it were the same as before, Kong Shucheng would yawn within two minutes. But now, on the tree of Confucian wisdom, the "branch of mathematics" has grown ten leaves. At this time, although he is not a "light boat has crossed ten thousand mountains", he is by no means the math rookie he was at the beginning.

I have to say that this is really a rare reading notebook.

In the notes, there are a lot of dry goods recorded.

Many of Huoyun Xueshen's problem-solving ideas, as well as his understanding of mathematical problems, are completely different from ordinary people.

For example, in the middle part of the notebook, Huoyun Xueshen also summarized a set of "mathematical universal problem solving methods", he used logical and meticulous mind maps, as well as unique language, to summarize several methods to solve problems: special value test method, extreme principle, elimination method, number combination method, recursive induction method, forward deduction cracking method, reverse deduction verification method, feature analysis method, valuation selection method.........

Interestingly, in the process of analyzing and solving difficult problems of sequences, inequalities, complex numbers, trigonometric functions, and solid geometry, Huoyun Xueshen also specially applied some proper nouns in "tomb robbery", "pesticide", "treasure hunting", "One Piece" and "eating chicken", which made Kong Shucheng can't help but laugh while watching. Then I thought about it carefully, and I felt that it was really like that.

What a talent!

It turns out that high school math can still be learned like this!?

Huoyun Xueshen is really a Metersbonwe-style scholar - "Don't take the usual path." ”

.........

From Jiefang Road to the bus station, it takes about 30 minutes by car.

During these 30 minutes, Kong Shucheng's eyes did not leave the notebook for a moment. Even, because he was too involved in reading, he laughed while watching, and was regarded as a "nervous disorder" by the passengers next to him.

Thirty minutes later.

Bus No. 193 finally arrived at the long-distance bus station.

Kong Shucheng also happened to read the notebook of the top student hastily. He stretched and was about to close the notebook, when he suddenly realized that the last piece of paper in the notebook felt a little wrong.

The last sheet of paper, which is significantly thicker than the others.

After a closer look, he found that the piece of paper turned out to be two in one.

Yun Yan used glue to glue the last two pieces of paper together carefully. Because the notebook is so thick, no one will find out about this secret without looking closely.

But why did Yun Yan do this?

Could it be that there is some kind of ulterior secret hidden in this two-in-one paper?

Kong Shucheng: "........."

I feel my heart beating faster.

After getting off the train, he found a place with fewer people outside the gate of the waiting room at the station. Seeing that there was no one around, he carefully tore off a corner of the paper, and then gently cut the two pieces of paper with the student card in his pocket.

The two sheets of paper, which had been sealed, were opened like a pocket.

Inside, there is actually a leaf hidden.

A completely yellowed leaf.

This leaf does not look very large, about 4 cm long and 2.5 cm wide, and is an extremely ordinary camphor leaf. Because it had been tightly sandwiched between two sheets of paper, it had been completely flattened and turned into a leaf specimen with clear veins.

Kong Shucheng pinched this leaf with his fingers, put the tip of his nose and smelled it, and he could still smell a faint fragrance of camphor trees. For some reason, he suddenly remembered a poem by Bai Juyi, the big sao Weng, "The old leaves are yellow like tender trees, and the cold cherry branches are white flowers." ”

"Hehe, this camphor leaf should be a love gift from a girl who has just fallen in love with Senior Brother Yunyan, right?" Thinking like this, Kong Shucheng couldn't help but want to laugh. Unexpectedly, Huoyun Xueshen was actually quite sullen.

Just as he was about to put the leaf back, he suddenly discovered an even bigger secret.

This secret suddenly made Kong Shucheng inexplicably nervous.

Because, on the smooth back of this camphor leaf, there are even a few lines of words written.

A sentence, to be exact, and a math problem.

That sentence is very short, only five words - "Buddha is destined to be a person"

And that math problem, Kong Shucheng almost couldn't understand it.

The topics are as follows:

Rank: The number of vectors contained in the greatly irrelevant group. Theorem: Let A be an m*n matrix, then the sufficient and necessary condition for r(A)=r is: the column (row) rank of A is r. Finally, r=5 m=1369"

The time for payment is August 22

.........

At that moment, Kong Shucheng felt that his heartbeat was speeding up in vain.

He didn't know what the Huoyun Xue God's sentence "Buddha is destined to do" and that obscure math problem meant. But what made him nervous was actually the date on the leaves.

August 23rd.

Obviously, this date is not the date before the college entrance examination.

And, judging by the handwriting on the leaves, this August 22 should be this summer.

And the date of the disappearance of the Fire Cloud God happened to be this summer.

.........

Kong Shucheng didn't have time to think about it, and immediately dialed Professor Yan Ran's mobile phone.

The call was quickly connected.

"Kong Shucheng, do you have something to do with me?"

"Sister Yan, I went to Yun Yan's house just now, and I also met his parents, and by the way, I transferred your 10,000 yuan to his father. ”

"Okay, thank you so much. ”

"Sister Yan, there is something I want to confirm with you. ”

"What's the matter?"

"What is the exact time of Yun Yan's disappearance?"

"August 25th. ”

“.........”

Kong Shucheng fell silent in an instant.

"Kong Shucheng, what's wrong with you?......... Why don't you speak? Didn't you, find any useful clues?"

Kong Shucheng looked left and right, and said in a low voice: "I found something in Yun Yan's notebook. ”

"What?!"

"It's a leaf. ”

"Leaves?"

"Yes, on the leaves, there is something written, and the date is exactly August 22nd. ”

"Kong Shucheng, can you send me a photo?"

"Well, okay, the light is a little bad here, I'll change places. ”

Kong Shucheng soon came to the door of a "real kung fu" restaurant next to the bus station.

It's half past seven in the evening, and it's really the peak time for dining, and there are people coming and going in front of the restaurant. In order to be able to photograph the contents of the leaves more clearly, Kong Shucheng found a dining table with good lighting.

"Click"

After Kong Shucheng finished taking the photo, he was about to forward it to Sister Yan when someone suddenly patted him on the shoulder from behind.

When I turned my head, it was a big man wearing a mask.

The big man nodded at him, then pointed under the table with his finger: "Young man, your card is off." ”

Well?

Kong Shucheng took a look and found that there was indeed a student card under the desk.

When I picked it up, it was my student card.

Odd!

Why did this student card, which was obviously in my pocket, fall out?

Kong Shucheng turned around and was about to say "thank you" to the big brother wearing a mask just now, but he was surprised to find that the person had disappeared. When he turned around again, the camphor leaf on the table was gone.

Vanish into thin air.

..................