APSIL -Chapter 164 The First Assignment of Jiuzhang Hall

Yesterday, Zhang Shou irresponsibly threw the topic of linear equations at Lu Sanlang and let him teach it.

This afternoon, he directly introduced two-variable linear equations.

Such a lightning-fast pace would have caused countless educational experts in his previous life to criticize him endlessly.

But now, facing a group of students who were at least sixteen years old, with the oldest nearly forty, he had absolutely no psychological burden.

They were all adults who had at least been baptized by The Nine Chapters on the Mathematical Art.

Something elementary school students could master in half a month or a month—he spent half a day teaching them.

If they still could not understand it, then they were simply stupid!

Of course, Zhang Shou did not merely explain theory.

He used examples such as:

• the classic “chickens and rabbits in the same cage” problem,
• the long-rope measuring well depth question that Wang Jie had encountered in the Shuntian Prefecture examination,
• the “using a bowl to determine the number of monks” problem,

and various other puzzles.

Through these examples, he fully demonstrated how two-variable linear equations could be flexibly applied to real-life problems.

Sure enough, when the students discovered that problems once considered extremely difficult could actually be solved so easily simply by setting up equations, they became extremely excited.

However, just as the two classes were about to end, Zhang Shou suddenly assigned a completely unrelated task.

“Among you, there may be some who have not memorized the Four Books and Five Classics perfectly, but the Thousand Character Classic should be something everyone has read.”

“You should also have studied many Tang poems, Song lyrics, and Han Yuefu poems.”

“When you return, recall what you have learned and see which lines from those poems, songs, and writings are entirely composed of characters from the Thousand Character Classic.”

“Write them down.”

“This assignment has a five-day deadline. You may submit it at any time within those five days.”

The other students thought Zhang Shou had simply become interested on a whim.

They assumed his purpose was to make them review poetry and literature while studying mathematics.

But Lu Sanlang absolutely did not think so.

The purpose of Zhang Kang inviting Zhang Shou two nights ago had not been explained to him afterward.

However, Lu Sanlang had known Zhang Kang for a long time.

Ever since returning to the capital and being praised by the emperor for his talent in mathematics, Zhang Kang had tested him with that mysterious locked box.

The result?

Lu Sanlang naturally failed.

He had not found even the slightest clue.

What mathematics? It was impossible!

Therefore, while following Zhang Shou back to the dormitory, he could not resist asking:

“Little Teacher, could it be that you have already found a clue regarding that fourteen-ring secret key?”

“Oh? You tried it too?”

Zhang Shou smiled.

After Lu Sanlang awkwardly admitted that he had no clue at all, Zhang Shou shrugged.

“I don’t have any clues either.”

“I’m just trying anything at this point.”

“First, I want to see how many famous poems from ancient times can be composed entirely using the one thousand characters from the Thousand Character Classic.”

“Then I’ll use the same algorithm I used before when Prefect Wang asked me to decode that secret letter and try my luck.”

After saying that, Zhang Shou shrugged again.

“If it works, then it works.”

“If it doesn’t, there’s nothing I can do.”

Lu Sanlang froze for a moment.

Then he suddenly slapped his thigh.

“How did I not think of that? This really is a method!”

“Teacher, you should have told me earlier!”

“Marquis Weinan already had people search for poems where every character came from the Thousand Character Classic.”

“But because they couldn’t match them with those fifty-six characters, they abandoned the idea.”

“Wait here. I’ll go to his place and bring you the copies of those poems!”

After saying this, Lu Sanlang turned around and was about to run.

But Zhang Shou suddenly had a thought.

He reached out and grabbed Lu Sanlang’s shoulder.

The total number of Chinese characters exceeded ten thousand.

Later generations estimated that commonly used characters numbered around 3,500.

Some statistics suggested that:

• 98% of daily written materials used only the most common 1,000 characters.
• 99% used around 2,500 common characters.

The Thousand Character Classic also contained one thousand characters.

Although many were uncommon characters, its coverage was still considerable.

Finding dozens or even hundreds of poetic lines composed entirely of those characters should not be impossible.

Of course, some common poetic characters such as:

“双” (double),
“若” (if),
“单” (single),
“涯” (shore),
“北” (north),
“烟” (mist),

were not included in the Thousand Character Classic.

This would certainly reduce the number of matching poems.

But regardless, asking his students to immediately organize all poems completely composed of Thousand Character Classic characters—even if they worked themselves to exhaustion, they still could not match Zhang Kang’s decades of effort searching for the secret of the box.

However…many people working together in Jiuzhang Hall might actually accomplish this.

With this thought flashing through his mind, Zhang Shou smiled when he saw Lu Sanlang looking at him in confusion.

“Since you are going to see Marquis Weinan, ask him something for me.”

“Could this matter he entrusted to me be turned into an assignment for the students of Jiuzhang Hall?”

“My personal ability is limited.”

“If even Teacher Ge and the other great scholars cannot solve it, I may not be able to either.”

“But if more people participate, perhaps we can find some ideas.”

Lu Sanlang opened his mouth.

Originally, he wanted to ask:

Those students who already struggle with understanding equations… how could they possibly help Zhang Shou?

But immediately, he understood.

Not to mention anything else—these students might discover poems that Zhang Kang had overlooked.

Furthermore, determining which numbered character each character in those poems corresponded to within the Thousand Character Classic required manpower.

Lu Sanlang certainly did not want to personally count every single character.

Most importantly…

Even the stupidest person might occasionally have a flash of inspiration and discover a method that intelligent people missed.

Of course, this depended on whether the secret code truly had something to do with poems and literature.

It might also just be a random sentence.

Immediately, Lu Sanlang straightened his chest proudly.

“I understand!”

“I’ll go now!”

“Teacher, don’t worry. If Marquis Weinan refuses, we’ll just casually deal with him.”

“After all, this is a problem from the Imperial Armory. It has nothing to do with us anyway!”

Zhang Shou naturally appreciated Lu Sanlang’s decisive attitude.

He nodded and told him to go quickly.

One hour later.

Zhang Shou saw Lu Sanlang enter excitedly, his eyebrows raised in delight.

He directly handed over more than ten sheets of paper.

“I knew Marquis Weinan would have these!”

“After discovering that all fourteen-ring characters came from the Thousand Character Classic, he immediately ordered thirty or forty trusted subordinates to search through poetry collections.”

“They spent more than half a month collecting these.”

“Of course, there may still be omissions.”

“But famous poetry collections should all have been searched.”

“They simply hadn’t had time to calculate the next step.”

“Also, regarding your suggestion of turning this into a Jiuzhang Hall assignment…”

“Marquis Weinan carefully considered it.”

“At first, he hesitated.”

“But after thinking it over, he seemed to understand and agreed to try.”

“Anyway, once the box is opened, apparently the password can be reset.”

“So there is no need to worry about it becoming unusable later.”

A box that can reset passwords?

Pretty advanced.

Zhang Shou thought this inwardly.

Then he took the papers and began reading.

With one glance, he noticed something.

Because finding poems containing all fourteen characters was extremely difficult, they had lowered the requirement.

Even poems with only seven matching characters were included.

For example:

“黄河之水天上来”
(The waters of the Yellow River come from heaven.)

The first character of the next line, “奔,” was not in the Thousand Character Classic, so the following line was excluded.

Another example:

“古来万事东流水”
(All things since ancient times flow eastward like water.)

The previous line:

“世间行乐亦如此”

contained the character “间,” which was not included, so it was excluded.

Another example:

“愿逐月华流照君”
(I wish to follow the moonlight shining upon you.)

The previous line:

“此时相望不相闻”

contained “望,” which was missing, so it was excluded.

Looking through those pages, poems containing all fourteen characters were extremely rare.

Even many five-character poems and lyrics with less strict structures had been included.

Clearly, Zhang Kang’s people had spent considerable effort.

Lu Sanlang explained: “As for the fifty-six characters on the lock itself, none of them could form a poem.”

Zhang Shou nodded.

After roughly reviewing everything, he said: “Tomorrow morning, check whether anyone in Jiuzhang Hall submits their assignment.”

“If they provide poems different from these, collect them.”

“If they are the same, don’t bother.”

“Then tell them this is helping the Imperial Armory solve a difficult problem.”

“Have them extract the number represented by each character in these poems according to the order of the Thousand Character Classic.”

Lu Sanlang listened while nodding.

By the end, he left confidently.

However, the clever Lu Sanlang did not keep this task to himself.

Currently, he was responsible for supervising morning lessons.

Qi Liang, meanwhile, spent his free time chatting with students one by one to understand their personalities and backgrounds.

Therefore, for such a large task, he naturally would not leave Qi Liang out.

After Lu Sanlang left, Zhang Shou spread paper across his desk.

He patiently converted the fifty-six characters on the fourteen-ring lock into corresponding numbers.

Then he tapped his fingernails thoughtfully.

“Instead of blindly trying substitutions…”

“Perhaps I could use this opportunity to teach functions?”

“If it’s a linear function, draw a Cartesian coordinate system and input the previous and following numbers…”

“That would also introduce analytic geometry.”

“Everything would become obvious.”

“Hmm…”

“Although that would be quite advanced…”

“And it would waste paper…”

Just as Zhang Shou prepared to use the manpower of Jiuzhang Hall to launch a large-scale code-breaking effort…

Marquis Weinan Zhang Kang’s urgent report also reached the emperor’s desk.

Regarding the box whose key had been lost since the reign of the previous emperor Ruizong and had never been opened again, the emperor was not as obsessed as Zhang Kang.

But he was still curious.

Therefore, he was not angry about Zhang Kang acting first and reporting afterward.

“Jiuzhang Hall has only been teaching for a few days, and Zhang Shou has already turned something Zhang Kang asked him to help with into a major assignment.”

“This kid…”

“Interesting.”

The emperor stood up.

Ignoring the cloak Chu Kuan brought him, he folded his hands behind his back and paced around the room.

“I heard the second prince went to see Zhang Kang?”

“Does he know about this matter?”

“Probably… not?”

Chu Kuan tried his best to make his answer sound uncertain.

Then he cautiously added: “After all, the second prince went to Marquis Weinan’s residence the morning before yesterday.”

“His meeting with the marquis happened before the two times Marquis Weinan met Zhang Shou, and before Lu Sanlang went to see him today…”

“Enough. No need to continue.”

The emperor interrupted lazily.

“The eldest and second princes have competed with each other since childhood.”

“Now that they are older, having other intentions is not surprising.”

“The eldest at least knows restraint.”

“He chose Duke Qin Zhang Chuan, a noble who only studies and compiles books without involving himself in state affairs.”

“But the second prince…”

“He dared to directly reach his hand into the Imperial Armory.”

Chu Kuan originally wanted to say:

Perhaps they simply wanted to show you their ability and ambition.

But seeing the emperor’s mocking expression, he swallowed the words.

Especially when he saw the emperor suddenly walk toward the door, Chu Kuan hurried after him.

He had originally planned to accompany the emperor to Qingning Palace to greet the Empress Dowager before resting.

He barely caught up before the palace hall entrance and helped the emperor put on the thick fox-fur cloak.

“You are the chief eunuch of the Directorate of Ceremonial, not a servant in the Qianqing Palace.”

“You don’t need to circle around me all day.”

The emperor said this without turning his head.

Chu Kuan was left awkwardly unsure whether to stay or leave.

But after watching the emperor walk more than ten steps away, he still followed.

As expected, the emperor did not chase him away afterward.

Not even after entering Qingning Palace.

When the emperor casually greeted the Empress Dowager, sat for only a short while, and prepared to leave, Chu Kuan finally relaxed.

But then…

The emperor, who had just stood up, suddenly asked two questions with a faintly amused expression.

“I heard Mother praised Zhang Shou highly in front of the eldest and second princes.”

“Interesting, isn’t it?”