Number theory is a branch of pure mathematics, focused on abstract theoretical research. Even most math majors won't encounter number theory during their undergraduate years; it's usually reserved for those who pursue further studies in this specialized field.
Although the scope of this field isn't exactly narrow, and some number theory problems are genuinely fascinating (well... at least to a select few—most people would probably say they're anything but fun), there's no denying one fact: number theory is a seriously, seriously, seriously deep and difficult field. If you want to set a tough problem in this area, you can easily make it so hard it'll bring people to tears.
Math teacher?
Sorry, no matter how many years you've taught high school math, number theory is absolutely the kind of advanced stuff that'll stump pretty much every math teacher out there.
And don't even get me started—John Yang just took a quick glance and instantly knew the score—this problem in front of him? It's... insanely tough!
"Hey, Charlie." John Yang decisively called his lifeline outside the room: "We've got trouble—the number theory problem here is way too hard. If I can't solve it, our infiltration mission is toast. Honestly, even with my skills, cracking this one is probably... Huh? You've got a way? Spill it, quick!"
Talk about a twist! No wonder he's a top-notch pro—he can still pull out a good idea at a time like this?
On the other end, Charlie mumbled with his thick accent, and John Yang immediately followed the old-timer's instructions step by step.
"First, get the phone online... How do I turn on mobile data again? Let me think... Oh, right, that's it. Okay, we're connected!"
First hurdle cleared, and John Yang couldn't help but breathe a sigh of relief.
"Next, download the 'Where You Don't Know, Scan There Smart Learning App'... Download what? From where? Online? How do I download from the internet?... Yeah, I only use my phone for calls and texts—my son usually handles this stuff for me... Don't get worked up, just explain slowly! App what? Store? Where do I even find the store? Wha... Oh, found it, found it, just click download? Hang on... All done!"
Phew... John Yang wiped the sweat from his forehead. He felt like fumbling through that download was the hardest step of all.
"Finally, open the app, scan the problem..." Sure enough, this last step was way easier: "Hold up the phone, aim at the question, swipe—and then just wait for the answer..."
"So, how's it going, Old Yang?" Charlie recommended his favorite app with the same pride Columbus had when he discovered the New World: "I'm telling you, Old Yang, you've gotta keep up with the times—these apps are just too convenient. Can't solve a math problem? Just scan it and boom, there's your answer. Next time you teach, remember this trick—don't let the kids get one over on you, haha! So, Old Yang, did you get the answer yet?"
On the other end, Old Yang paused, his voice tinged with a mix of gloom and barely contained frustration: "What kind of half-baked nonsense did you just recommend... Never mind, sigh. Got anything else? Like in the movies, where I use my glasses to send a signal and the headquarters think tank instantly fires up their brains and crowdsources ideas?"
"Sure," Charlie confirmed. "Those glasses you're wearing can do that—I just turned the function off, but I can switch it on anytime. But..." Charlie's tone grew cautious: "The moment we connect to the database, headquarters will immediately know where we are and what we're doing. We'll lose our stealth status. If headquarters gets our info..."
"Leak our location?"
"Not much risk of leaking info, but the odds of embarrassing ourselves are sky-high."
John Yang fell silent.
If they called headquarters and uploaded their data, headquarters would instantly discover that these two old guys had snuck off to the front lines—and gotten stuck on a math problem. Would it mess up the operation? Spark a rescue mission? Trigger a chain reaction? John Yang could imagine all of it. And if that really happened, no matter what came next, he and Charlie would be forever branded as 'meddlesome old fools who bite off more than they can chew.'
Honestly, he didn't care about reputation.
Honestly, nothing matters more than life itself.
Giving up a safe and reliable plan just for a bit of pride? That's not what a wise person would do. But... why, at this very moment, does he not want to play it safe?
John Yang took off his glasses, closed his eyes, and pinched the bridge of his nose. Memories flashed through his mind—old ones, older ones, even older ones—waves of precious recollections flooding in. The pride of being a father, the confusion, the responsibility, the helplessness, and finally, the last struggle of fatherhood.
Beep, beep—the timer on the screen ticked away, second by second. An hour and a half for solving the problem seemed plenty, but for this number theory question, an hour and a half was barely enough for a real number theorist to brush their teeth and whet their appetite.
This really was a super tough problem.
But... why, at this very moment, does he suddenly feel a surge of hot-blooded passion blazing up inside him?
"I'll contact you again within an hour. If things go south, come save me." Calmly arranging his backup plan, John Yang hung up the phone. He pursed his lips, but in his heart, he silently said: "Xiao Qi, there's something I've always been proud to tell you, and today I'll say it again: Back then, in our whole county, only three people made it to college. And your dad? I had the highest score. Sure, I never competed anywhere bigger, and ranking wasn't a thing back then, but looking back, I guess you could call me the county's top scorer."
"Being the county's top scorer isn't much, but there's one thing I'm even prouder of. My teacher—he was branded a rightist during the Cultural Revolution, sent from Beijing to the provinces, and ended up teaching at a university. He might not've looked impressive, but only a handful of favored students knew the truth: He was actually a disciple of the great mathematician Hua Luogeng. Which means—"
Hua Luogeng is my academic grandmaster.
Chen Jingrun is my academic uncle.
Even though, for political reasons, I ended up teaching high school in a small city, your old man still had his moments of glory.
I once loved math so much—grinding away in college lectures, digging deeper under my teacher's guidance. My teacher used to praise my extraordinary insight and unyielding character, saying I had a bright future ahead. He led me into the world of number theory, and I even got my hands on a notebook from my academic uncle. Oh, I remember now—Stephen Evenson, that familiar name, I first saw it in that notebook.
My academic uncle once met Stephen Evenson at the International Congress of Mathematicians, and they had a brief exchange.
There's no record of who won—science isn't about winning or losing. But you can't hide the pride that comes through in every word.
So—shoop—John Yang opened his eyes, his gaze turning cold and sharp.
Staring at the problem before him, long-buried memories bubbled up from the depths of his heart, popping and crackling.
Even if I sent this problem back to the so-called think tank, could they solve it?
Even if I don't send it back or ask for help—can I, John Yang, really not solve it myself?
Looking back, everything he needed was ready on the boss's desk beside him: paper, pen, tools, nothing extra. John Yang turned, sat down, and hunched over the desk, ready to write.
The seat was just right, the lighting was perfect, and the feel of pen and paper was spot on. Turns out, even though Stephen Evenson had fallen to the so-called Night Emperor, he never forgot the pride and self-respect of being a mathematician.
Good, very good. In this heart-pounding calculation, John Yang suddenly found himself back in his college days. Times were tough, summers were sweaty, but hunched over his desk, scribbling away, his eyes shone with a mix of excitement and mania. It was like sparring with a master, like chatting with kindred spirits—every symbol on the page became the most beautiful note in the world.
Colors faded, shapes disappeared, time was forgotten—nothing existed except pure mathematics and pure persistence.
Time ticked by, and the threat of death crept closer. But John Yang's hand stayed steady, and his eyes stayed sharp.
No, not just sharp—sharper than ever. Like a legendary sword rusted by time, slowly polished until the tarnish is gone and the edge gleams again.
Self-destruct on the spot?
Screw your self-destruct on the spot!
Almost there, almost there—I can feel it! That soul-deep shiver, that thrill from the bottom of my heart, that joy running through my whole body—this problem is about to crack wide open!
THE_ZONE, activate!
THE_SEED, activate!
THE_LOCK_OF_DNA, activate!
Today, I, John Yang, am going to smash this number theory problem to pieces!!!
Zzzzzzzzz—
"Dad!" Suddenly, a familiar voice snapped John Yang back to reality, just as his eyes were about to shoot lightning. Exiting his super mathematician state, John Yang looked up in confusion—only to be shocked to see his white-haired daughter standing right next to him. No, not just standing—she'd actually walked out of the secret door he'd been trying to open.
"You..." John Yang stammered, "How are you here?"
Jill Young shot back, "Why shouldn't I be here?"
"That Stephen Evenson..."
"Already taken care of—he was handled nice and neat three days ago. Agent Okamoto is getting better and better; finding people this time was a breeze."
Already... already handled?!
John Yang's eyes glazed over.
Did I just... waste all that effort?
No, it's not just wasted effort.
Jill Young, for once not joking around, wore a rare serious expression. "Dad, why are you here? Were you kidnapped? Threatened? Tricked?"