“Oppa, why is the sky blue?”
Seoeun asked as she looked up at the sky in the yard.
“Sunlight is actually made up of all the colors of the rainbow mixed together. But when it passes through the sky, blue scatters the most, so it looks blue to our eyes.”
Six-year-old Seoeun had reached a stage of growth that children her age typically entered.
The so-called “Why stage.”
Just as the name suggested, she showered everyone with questions without end. But Seoha’s answers never once faltered.
“Then where did all the other colors go?”
Seoeun brought her index finger to her slightly parted lips.
Finding her adorable, Seoha gently stroked his little sister’s head.
“Red and yellow travel straight ahead and come directly to us. That’s why the sun sometimes looks red, too, right?”
“Oh! I get it.”
Seoeun clapped happily, then ran around the yard.
Seoeun loved her older brother more than anyone else in the world.
Though Seoeun’s questions followed one after another dozens of times a day, Seoha had never once replied that he didn’t know.
Her kind older brother who knew everything.
Whenever Seoha was away from home, Seoeun would sneak into his room and play.
Miyoung knew how sensitive Seoha was and warned her daughter, “You’re not allowed in there until your brother comes back!” But it was useless against Seoeun.
Creak.
The door slowly opened. Seoeun looked around, then poked her little face through the gap.
‘Mom’s in the vegetable garden.’
Seoeun quietly opened the door and went inside. Then she plopped down in front of the bookshelf that filled one entire wall.
Looking up at it made her neck hurt. There were far too many books.
“The encyclopedia of animals is… here!”
Seoeun dragged over a chair and pulled out a thick book.
Whenever she looked through an encyclopedia, she would sometimes discover notes Seoha had written in pencil. Seoeun was searching for them one by one as though she were hunting for treasure.
“I looked at desert animals yesterday, so today it’s sea animals… Sea… sea…”
With her small hands, Seoeun turned the pages one at a time. Then she found what she wanted.
“Here it is!”
Her brother’s handwriting.
[Penguins actually have knees. They’re simply hidden beneath their feathers.]
[Whales are mammals, so they nurse their young.]
[An octopus has three hearts.]
“Huh? Three hearts?”
Finding it uncomfortable to sit, Seoeun lay down on her stomach and turned the pages, moving her finger along her brother’s handwriting.
There were plenty of notes in the mathematics encyclopedia, too, but they were filled with numbers and symbols Seoeun couldn’t read, so she quickly lost interest.
The next day, Seoeun was rolling around on the floor of her brother’s room again.
Bored, she rolled toward the drawers. Then she remembered her brother storing something here.
Rattle.
When she opened the drawer, she found a notebook she had never seen before, tucked away in the back.
“What’s this?”
Seoeun tilted her head and took out the notebook. Nothing was written on the cover.
“Wow!”
When she turned to the first page, Seoeun’s eyes grew round and she let out an exclamation of admiration.
It was a drawing by her brother.
A man wearing a duck mask filled the entire page. Only his lower face was exposed, much like Batman, making him look like a comic-book character she had seen somewhere before.
The drawing was in black and white because it had been done in pencil, but the mask had been colored yellow. Strange mathematical formulas floated around the man.
Intrigued, Seoeun examined the drawing closely.
The man looked frightening somehow, yet he also seemed familiar. He was wearing the duck mask that both Seoeun and her brother loved.
“When Oppa gets back, I should ask him to play dress-up with me.”
Seoeun carefully returned the notebook to its original place. Then she hugged the duck doll her brother had given her and went outside.
* * *
“Time’s up! Please put down your pencils.”
With the proctor’s declaration, the first day of the competition came to an end—a long four-and-a-half-hour journey.
The sound of pencils being set down could be heard throughout the examination hall. But there was no sign of relief on the students’ faces. Instead, a heavy, despairing atmosphere dominated the room.
The students handed in their answer sheets and rose from their seats. Shock and bewilderment were plainly visible on most of their faces. Some students still couldn’t stand, clutching their heads, while others stared blankly up at the ceiling.
“What was that?”
“It was completely different from the past problems!”
“Was that really right? It was way too difficult.”
Murmurs arose from all around the hall.
“Hah… hah…”
Luichen panted heavily.
It had been a very long time since he had experienced running out of time while solving a problem.
He had spent two hours on the first problem alone.
Wasting time on the wrong approach at the beginning had been devastating. If it had been an ordinary number theory problem like those he usually encountered, thirty minutes would have been more than enough, no matter how lengthy it was.
The key to the problem had not been number theory.
The usual approaches had been completely ineffective. He had tried factorization, modular arithmetic, Diophantine equations (Diophantine equation * an indeterminate polynomial equation for which only integer solutions are sought), and every other method he was familiar with, but he couldn’t even find a clue.
It was only when the word “give up” began to flicker through his mind that he realized he needed to approach it through algebraic number theory.
‘Though it was far too late.’
Perhaps because he had been pressed for time, he had been unable to properly demonstrate his ability on the geometry problem, his specialty.
He had barely found the answer and was in the middle of solving the third problem when time was called.
Luichen looked around.
Most of the students hadn’t even solved the first and second problems, let alone the third.
‘Are they trying to hold China back?’
Perhaps China’s excellent results the previous year had been the problem.
If the problems were too difficult, they could actually become less effective at distinguishing between competitors.
‘This is nowhere near enough.’
No matter what kind of problems appeared, Luichen was confident he could perform better than anyone else in this room.
It was a confidence he could possess because he had been born with extraordinary talent and had worked harder than anyone else.
“Luichen, how did it go?” one of his teammates asked cautiously.
“…”
Luichen didn’t answer.
“I barely managed to do the first one. And I’m not even sure it’s right.”
“I didn’t even get to look at the third problem.”
One by one, the team members gathered and shared their impressions.
He had expected it, but their results were even more disastrous than he had imagined.
‘Does this mean their plan to hold China back worked?’
Though they were gifted students selected from across China, they had been unable to escape the limitations of rote education.
But that was probably true of every country.
In the end, Luichen thought, all he had to do was get the highest score.
“Why are those guys smiling?”
One of his teammates pointed toward the Korean team’s seats.
“It was absurdly difficult.”
“But the principle Seoha told us about came up, so I think I got that one right.”
“That study group really helped, didn’t it?”
“Considering the difficulty, I think I did fairly well.”
The Koreans chattered among themselves in words Luichen couldn’t understand.
Yet there was something strangely excited in their voices, and Luichen sensed an uncomfortable energy.
Dokyung hugged Seoha and patted him on the back.
Judging by the level of the Korean team as Luichen knew it, it would be difficult to expect good results from them. But one thing was certain: they had not simply ruined the exam.
“Let’s go.”
The conditions were the same for everyone, anyway.
He had failed to manage his time today because he had misread the direction of the problems, but there was still another day remaining.
* * *
“Seoha!”
Sujeong called out to Seoha, who was walking ahead.
Seoha naturally slowed his pace and matched his steps to hers.
Sujeong’s expression looked bright.
“It seems like you did well on the test?”
She had been about to ask him, as she usually did, “How did you do?” but stopped herself. Seoha was simply on another level.
“It’s thanks to you. The old me would have been defeated by the first problem. Do you remember? When we first met.”
“Oh! That time?”
Perhaps he had thought of something, because Seoha looked at Sujeong’s face and chuckled.
It was not a pleasant memory, and Sujeong’s face flushed red.
“N-no, not that! I mean when I asked you for a proof after the test.”
“Of course I remember.”
“I can feel how much I’ve improved since then. No matter what kind of problem I encounter, I try to look at it from a different perspective.”
“I like that about you, Noona.”
“W-what?”
Sujeong jumped in surprise.
“You’re like the mathematicians of the past.
“You think things through to the very end on your own, and even when you run into a dead end, you never give up. That’s how you looked to me when you focused on that one problem you couldn’t solve until the exam ended that day.”
Unable to hide her embarrassment at Seoha’s praise, Sujeong changed the subject.
“Oh, you really like mathematicians from the past.”
Perhaps it was a topic he had always been interested in, because Seoha’s expression grew serious.
“I think about them, too. About how I must never give up.”
Joseph Fourier devoted his entire life to proving the heat equation, for which he became known through Fourier analysis.
The equation was completed only after his death, by Dirichlet, Riemann, and others. It was truly an incredible display of perseverance.
“Is there a problem you want to give up on, too?”
From Sujeong’s perspective, there was no theory Seoha didn’t understand and no problem he couldn’t solve. If even he wanted to give up, what on earth was he working on?
“Of course there is. But I’m not going to give up.”
From Seoha’s attitude, Sujeong realized that he had no intention of telling her what was troubling him.
‘When did he become so mature?’
Standing close to him, she realized that they were already nearly the same height.
When she had first met him at the competition the previous year, she had thought of him as nothing more than a child, but…
In the past, Sujeong had not wanted anyone to move ahead of her.
But now, simply keeping up with him left her breathless, leaving her no room to think about anything else.
‘Soon, I might not even be able to see him.’
She did not know it herself, but perhaps Seoha was already impossibly far ahead.
The sudden surge of anxiety made her chest feel tight.
“Noona, are you all right?”
“Yes. Nothing’s wrong.”
Perhaps she had been taking it all too lightly.
Sujeong thought that following Seoha might be something far more remarkable than she had imagined.
* * *
Footsteps echoed through the dormitory hallways from before dawn.
Students who had risen earlier than usual—or perhaps had not been able to sleep—moved about quietly.
On the second day, with yesterday’s shock still fresh, everyone was tense.
Seoha noticed that some of the students’ eyes were swollen, as though they had cried through the night. He was not the only one who had placed a great deal on this competition.
The seats and desks were the same as yesterday, but the atmosphere was completely different. Everyone’s nerves were stretched taut.
At last, the proctor appeared carrying the problems.
The final examination of the competition began.
Flutter.
Seoha opened the test paper.
‘Hmm?’
As he skimmed the problems, the last one seemed strange.
The answer was not immediately apparent.
‘Oh-ho!’
At last, a problem worth solving had appeared.
He could feel Ducky struggling, eager to solve it himself.
‘No.’
Seoha lightly suppressed Ducky.
Unable to overcome his curiosity, he began solving the sixth problem immediately.
It was a type of problem he had never seen before, but Seoha felt a sense of déjà vu. As if he had seen something like it somewhere before.
‘Ah! The sixth problem from 1988!’
It was exactly the feeling he had gotten when he saw that problem.
A smile spread across Seoha’s face.
And soon, he became immersed in his own world.