Keyboard Immortal

Zu An chuckled at Yang Wei’s expression. He looked like he was about to burst a blood vessel. He said to the teacher, “There’s a very easy way to resolve this situation. I’ll set twenty questions too. Regardless of whether you cheat or guess your way through, as long as you can solve them all... Forget it, I’ll give you a discount. If you even solve half of them, I’ll pack up my stuff and get out of the academy immediately. If you don’t, I will hold you to your earlier wager. How does that sound?”

No matter what, Yang Wei was still an official of the royal court, and a teacher officially hired by the academy. Neither Zu An nor the academy was in a good position to terminate him over a mere bet. However, what if Yang Wei couldn’t even answer a single question Zu An set? No matter how shameless he was, there was no way he would suffer the ignominy of staying in the academy.

Yang Wei was taken aback by the sudden proposal. He was intimidated by how Zu An had managed to easily solve all twenty questions, and his confidence was rapidly deflating.

Shang Liuyu took this opportunity to chime in, “Teacher Yang, surely you can’t be intimidated by your student, right?”

“Of course not!” Yang Wei immediately straightened up. “Do your worst then! I’ll solve even 200 questions if that’s what it needs to make you submit!”

This wasn’t a bad bet to make. Even if he was not confident in solving all twenty questions, at the very least, solving ten of them would be well within his capabilities. He was a renowned arithmetic expert in Brightmoon City after all, having calculated years of taxes for the Civil Affairs Department. There was no way a young punk’s questions could trip him up. As long as he succeeded, he would be able to send Zu An packing from the academy!

Zu An had an inkling of what Yang Wei was thinking based on his reaction, and he smiled to himself. I shall show you the horrors of mathematics then!

There were many plausible questions he could come up with, but he decided not to use the less-mainstream geometry questions. He doubted anyone in this world knew about pi, calculating the area of a circle, and that sort of thing. Setting those questions would only make the others think he was intentionally making things difficult for Yang Wei.

In order to crush Yang Wei thoroughly, what he had to do was to come up with questions that everyone understood, but were unable to solve. Got it!

With quick, deft strokes of his brush, Zu An wrote out twenty questions in a flash. He handed the sheet of paper over to Yang Wei with the sincerest of smiles. “Since you’re a renowned arithmetic expert, I trust that these questions wouldn’t pose any problem to you.”

Yang Wei was surprised by Zu An’s sudden humility. He cleared his throat. “Of course. How difficult could questions coming from a junior like you be?”

He took the paper and read the first question:

‘There are two numbers, each between 1 and 20. The sum of the two numbers is given to Person A, and the product of the two numbers is given to Person B. Person A told Person B that he didn’t know what the two numbers were, and Person B said that he didn’t know either. With that, Person A said that he knew the answer now, and Person B replied that he knew the answer too.

‘What are the two numbers?’[1]

Based on the questions Yang Wei had come up with, the concept of multiplication did exist in this world, so it wasn’t out of the syllabus.

Yang Wei blinked his eyes several times after reading the question. What the hell is this? I’ve never seen such questions before! T-this... How the hell do I solve such a question?!

The question looked simple enough at first glance, but as he tried to solve it, cold sweat began dripping from his face. Despite the knowledge he had accrued throughout his entire life, he found himself unable to figure out a way to solve this question!

The surrounding students also began discussing the question.They had never seen such a novel question before. However, even after racking their brains for a long while, they had no idea where to begin.

“Silence!”

Yang Wei was hoping for some inspiration from the students around him, but most of their discussion was nonsensical, contributing nothing. This made him incredibly frustrated.

The students stuck out their tongues at him in response. You’re the one who can’t solve the question. Why are you venting your frustrations on us?

Yang Wei’s face turned as black as charcoal at their mutterings. It was then that he realized there were only twenty numbers in total. At most, I’ll just try the numbers one by one. I reckon that’s how that fellow solved my questions earlier!

He quickly composed himself and proceeded with his calculations.

The students looked on as he began working through the problem, feeling deeply impressed. As expected of the teacher. He managed to find a way to work out the answer in just a few moments.

Meanwhile, Zu An was sitting cross-legged on a chair, calmly sipping a cup of tea which Wei Suo had brought out from god-knows-where. His eyes were fully on Shang Liuyu, appreciating her marvelous figure. He’d met quite a few beauties after coming to this world, but even he had to admit that her charm was the real deal.

Shang Liuyu, on the other hand, was focused on the question. Even though she was a foreign language teacher, she still knew a thing or two about arithmetic. She had been able to solve most of Yang Wei’s questions earlier, but the question Zu An devised was simply too bizarre. No matter how she thought it through, she couldn’t make heads or tails out of it.

She threw a discreet glance at Zu An, only to see him staring at her. She was amused by how his attention was wandering despite being in the midst of an important bet. This lad sure is confident in himself. He really is different from the others.

In contrast to Zu An’s relaxed demeanor, Yang Wei’s clothes were completely drenched in sweat. He’d made some initial progress through trial and error, but the more he progressed, the more muddled he became. Somehow, every answer he arrived at didn’t seem right to him.

He swallowed and shot a look at Zu An, who stared back at him with an enigmatic smile on his lips. All of a sudden, it struck him. This fellow must have intentionally put the hardest question in front to trap me! I nearly fell for his ploy!

Yang Wei decided to move on to the next question. He would return to this one later on.

He flipped over to the second question, and this was what he saw.

‘There are three doors in front of you. Behind one of the doors is a treasure, but there is nothing behind the other two. After you select a door, someone opens one of the two remaining doors, revealing an empty room. Then, the person offers you the chance to switch to another door. To maximise the probability of choosing the door that hides the treasure, would you switch to another door? Please state the reason behind your decision.[2]

Yang Wei was delighted.

That fellow has indeed put the hardest question in front. This is much easier! Hmph! Isn’t the probability the same regardless of whether I change doors or not? He even tried to mislead me by phrasing the question to make it seem as if there’s a better decision. Do you take me for a fool?

He quickly wrote down ‘I won’t switch to another door’. However, still worried that his answer might be too ambiguous, he jotted down ‘Regardless of whether I switch doors or not, the probability of selecting the door with the treasure is the same’.

Satisfied with his answer, he moved on to the third question.

‘Five pirates managed to obtain 100 ki stones in a raid. Pirate A was given the right to decide how to distribute the bounty, but the proposal he comes up with must be agreed upon by more than half of the pirates in order for it to be accepted. Otherwise, he would be thrown into the sea, and Pirate B will be given the right to determine the distribution, with the same rules applied. Assuming that you’re Pirate A, how should you distribute the ki stones in order to maximize your gain?

‘Please assume that the pirates are rational arithmetic experts, and they’re able to accurately calculate their gains and losses to decide on the best course of action that maximizes their gains.’[3]

Yang Wei was stunned. Just what in the world is in that fellow’s mind for him to come up with such weird questions?

His first response was to equally distribute the ki stones among all the pirates, but he soon threw out the answer and tried to calculate other possibilities.

The surrounding students also launched into fervent discussion, but none of them had a clue what the optimal distribution for Pirate A was.

Shang Liuyu found the use of the term ‘pirates’ in the question rather endearing. This lad sure comes up with interesting questions.

After struggling for a while, Yang Wei took out his already-soaked handkerchief once more and wiped his forehead. He was in full-blown panic. He couldn’t find a way to verify whether his answer was right or not.

Should I move on to the next question?

Yang Wei remembered how Zu An had chosen to put the hardest question in front, and he figured that the questions behind should be easier. Taking a deep breath, he proceeded with the fourth question.

‘Five prisoners, numbered from 1 to 5, take turns to draw green beans from a rucksack filled with 100 green beans. The rules state that they’ll have to take at least one green bean. The prisoners are not allowed to communicate with one another, but they are able to count the number of beans left in the rucksack through touch. Which of the five prisoners has the highest chance of survival? All the prisoners who end up with the most beans and all with the least beans will be sentenced to death.

‘Note:

1) All of the prisoners are smart, rational people who will decide on the best course of action for them.

2) Their primary aim is to survive. If that is not possible, they will aim to kill as many people as possible.

3) There’s no need to fully distribute all 100 green beans amongst themselves.’[4]

Yang Wei nearly burst out cursing on the spot. What is this dumb question? Why are there so many rules here? The question looked simple at first glance, but if one were to start thinking about the specifics, there were so many factors to consider that it could blow one’s mind.

He spent a while attempting to work out a solution before eventually giving up and moving on to the next question.

‘There are 100 people on an island. 5 of them have red eyes and 95 of them have blue eyes. This island has three weird rules:

‘1) They are not allowed to look into mirrors or any other reflective surfaces, so they aren’t able to determine their own eye colors;

‘2) They can’t tell others what their eye colors are;

‘3) Once a person realizes that he has red eyes, he would have to commit suicide that very night.

‘One day, an adventurer arrived on the island. Oblivious to the rules, while he was partying with everyone else, he accidentally let it slip that “Some of you have red eyes”.

‘Assuming that everyone on the island is smart and capable of logical deduction, what do you think will happen on the island afterward?’[5]

Yang Wei’s eyes lit up. This question was much easier than the ones before. He grabbed his brush right away and began jotting down his answer.

...

...

...

Just like that, with bouts of smiles and bouts of stress, he went through the questions one by one. Eventually, he realized that he was only able to solve a few of them.

By this time, a huge crowd had formed outside the classroom. Classes had already ended, but to everyone’s astonishment, none of the students from the most mischievous Yellow class had left yet. Out of curiosity, the students from the other classes decided to head over to take a look. It didn’t take long for news of the bet between Zu An and Yang Wei to spread around the entire academy, drawing in massive crowds.

If it was only a simple duel between Zu An and Yang Wei, the proud prodigies of the Sky class wouldn’t have bothered. However, the presence of Shang Liuyu changed things.

Shang Liuyu was the most popular teacher in Brightmoon Academy. Her classes were always packed to the brim, and her students were always incredibly focused. Their eyes were simply too caught up in appreciating her beauty to be distracted by anything else.

Some of the students came to watch the drama, but the majority flocked over to ogle Shang Liuyu. However, it didn’t take them long to be drawn to Zu An’s questions.

What was interesting about Zu An’s questions was that they were very easily understood. Most of them felt that the questions were easily doable, and they naturally began to discuss the possible solutions with one another. Even the prodigies of the Sky class, who were usually only interested in cultivation, began making their own calculations too.

“Brother-in-law, you’re the best!”

Chu Huanzhao wasn’t one to miss a commotion, and she seemed oddly proud about the situation. It was almost as if she was the one in the limelight right now. She didn’t question her feelings; she put them down to a shared sense of glory with a fellow Chu clan member.

The adorable Ji Xiaoxi was also standing amidst the crowd, poring over the questions with interest. The slight frown on her face did little to mar her beauty. How are these questions supposed to be solved? Should I go back and ask my father about them? Ah, but father isn’t interested in this kind of thing. He only fancies those perverted magazines he has stowed in his room. He seems to have gotten a new book recently, and he’s being very secretive over it. He doesn’t even allow me to come close to it. Hmph...

Pei Mianman, dressed in a black cloak that concealed her proud figure, was also watching the spectacle. Her lips inched up into an amused smile. This fellow sure is an interesting one. Chu Chuyan does have a sharp eye for people. Should I find an opportunity to nab him over to my side? It should be interesting to take her stuff away from her...

Hiding at the very back of the crowd was Zheng Dan, who was feeling particularly flustered. The reports she had browsed through depicted Zu An to be a good-for-nothing, and she had put his big win at the Silverhook Casino down to an incredible bit of luck. She hadn’t expected Zu An to be this skilled in arithmetic.

It looks like it wasn’t just luck at play at the Silverhook Casino. I reckon that even Yang Wei will be done in by him. I sure do wonder who was the one who sent Yang Wei after him, though.

Still, I should probably proceed carefully from now on, lest my honey trap backfires on me.

After what seemed like forever, Shang Liuyu issued a reminder to the embattled arithmetic teacher. “Teacher Yang, time is already up.”

Yang Wei wiped off the sweat on his face. “Give me a while more, I’m just about finished.”

All along, he had been the one to see students struggling to solve his questions under the time limit. Who knew he would be put in the same position one day?

However, with so many spectators, he couldn’t bring himself to shamelessly drag things out for too long. He made a few final strokes with his brush, then put it down and said, “I’m done.”

To be honest, he had no confidence in all but two of the answers he had written down. However, he still felt he was in with a chance. At the very least, he should be able to get ten questions correct.

He was relieved that he hadn’t declared arrogantly that he would get all twenty questions right. If so, it would already be all over for him. As long as he could get ten questions correct, he would be able to salvage some of his pride. After all, everyone here knew just how difficult the questions were.

“How is it? I managed to at least get ten of them right, didn’t I?” Waiting calmly as Zu An checked his answers, Yang Wei slipped his sweat-soaked handkerchief back into his pocket, a triumphant smile emerging on his lips.

He was confident that no one in the entire Brightmoon City would be able to fare better than him on the test—well, except for Zu An the pervert, anyway.

“As expected of Teacher Yang, he managed to answer all of the questions!”

“Wow, that’s really impressive. I don’t even know how to answer a single question at all.”

“Teacher Yang is not our arithmetic teacher for nothing. How can he hold his own without possessing some skill?”

“Still, I must say that the questions Zu An came up with are truly tough. His proficiency in arithmetic is at least on par with Teacher Yang.”

“I reckon it’s just Teacher Yang going easy on him. There’s no reason for him to take a student so seriously, after all.”

...

Yang Wei’s back slowly straightened with pride as he savored the commentary coming from the surrounding students. It seemed he had managed to build up quite some prestige for himself over the years. He patted his chest and turned to glance at Shang Liuyu, relieved that he had at least managed to salvage his reputation in front of her.

However, Shang Liuyu wasn’t looking at him at all. Her eyes were fixed intently on Zu An, curious as to what the results would be.

Zu An finally broke his silence. “Is this the level you’re at? It looks like I’ve overestimated you. You didn’t even manage to get a single question correct!”

The classroom erupted in chaos.

“What?” Yang Wei swore that he was hearing things. There’s no way I could have gotten everything wrong! He glared at Zu An in aggravation as he hollered furiously, “Lies! How dare you slander me!”

You have successfully trolled Yang Wei for 1024 Rage points!

He had been feeling good about himself just a second ago, but now, practically everyone in the academy heard the announcement that he hadn’t gotten a single question correct. This sudden nosedive his emotions took was simply too great for him to bear!

1. The Impossible Puzzle, first published in 1969. The name of the puzzle was coined by Martin Garnder in his formulation of it in 1979. There have been several formulations of this puzzle since.

2. This is the famous Monty Hall Problem.

3. This is the Pirate Game, a simple puzzle in Game Theory.

4. The only reference to this puzzle I can find is online at http://perplexus.info/show.php?pid=3759&cid=29062

5. This is one of the formulations for the Blue-Eyed Islanders Problem.