Monogatari Series - Volume 17 - Chapter 2.10

010

“And so, your chances of getting it right are higher if you switch from envelope a to envelope c. Twice as high. They call this the Monty Hall problem,” the girl finished explaining, and now it finally made sense. I felt like shouting out loud.

This is fun!

That was my reaction─the first time since elementary school that I felt like studying could be fun. Even if getting good grades was the right thing to do, I wasn’t having any fun. Sure, getting a 90 made me happier than getting an 80, but it just wasn’t the same.

Listening to her explanation, I discovered that studying could be fun─and that seemed far more valuable than anything else I’d been learning. This of course had to be in part because of how skilled the girl was at teaching.

Conveying a problem whose solution is at odds with our intuition, like the Monty Hall puzzle, is difficult─take how I tried and failed with Ogi, for instance.

“This is fun!” I had exclaimed. Out loud.

Yes, this was before I grew bitter, before I gave up, before I washed out, back when I was straightforward. I was more affable than I am now, but not the type to be so honest about his feelings with a stranger.

I must have found it just that fun.

It was shocking.

It’s okay for studying to be fun─the idea had never occurred to me. I would have found it immoral, somehow criminal.

If you asked police officers devoted to justice─one of my parents, or someone else, it doesn’t matter─why they carried out their duties, they’d get bashed for replying, Because it’s fun. If a politician whose actions affect a nation said politics is fun, the remark could even be used to force a resignation.

Likewise.

You should never say that studying is fun─I thought it was forbidden.

But in fact.

The girl’s explanation was fun─so much so that I wanted to scream.

It was like the first time I ever read a novel. I’d vaguely seen comics as fun and novels as serious, and having my ignorance shattered was refreshing.

Of course, the Monty Hall problem wouldn’t show up in a middle-school math class, so it wasn’t directly connected to my coursework. That didn’t matter, though.

Before I knew it, I was asking her, “Are there any more problems like that?!”

“Yup. Lots of them,” she replied with a smile. “I can teach you as many as you want. As long as you promise to love math even more. As long as you keep loving math.”

I was happy.

Her words made me happy─to be clear, young Araragi was close to hating math after receiving those miserable results on his final exam. He nearly hated this new subject, nothing like the arithmetic he so excelled at in elementary school─but that was all wiped clean from his mind. He even felt as though he’d loved math since he was born, ceaselessly.

It was a bit extreme, even for a child’s thoughts.

I’ll admit that myself.

I might have chewed out any guy who flip-flopped like that, whether or not he tried to hide it. Meanwhile, the girl didn’t look bothered in the least when I swore to unconditionally love math.

“Okay, then,” she said. “Starting tomorrow, let’s keep on studying here together.”

I could keep on loving math.

To jump to the end of this story, I upheld my vow. Even after my grades plunged to a washout’s at Naoetsu High, I maintained at least a certain standard in math.

But I’d forgotten my all-important vow until just now.

I’d forgotten the cause, producing only effect.

What to make of that?

“It’s getting late, Araragi, so I’ll just give you some homework. Think about it on your own, come up with an answer, and return here on your way home from school tomorrow.”

“Huh? Oh, okay.”

My faint disappointment that today was coming to an end was overshadowed by excitement: there was not only a tomorrow, there would be many tomorrows.

“It’s a promise. Promise you’ll come. That you won’t get bored of math.”

“Yeah. I get it.”

“Then here’s your question,” the girl said, pulling five cards out of her pocket. It seemed she had prepared this “homework” for young Araragi in advance.

There seemed to be numbers, symbols, letters, and kanji characters on both sides of the cards. Without showing them to young Araragi, the girl lined them up on the floor of the derelict house.

“There are five cards here. What is the minimum number of cards you have to flip in order to prove that a number is always on the opposite side of a card showing a character?”