Kantan na Monitor desu

I had to win.[1]

I had tried every available option. I had lost everything: my money, my social standing, and all the many people I had called friends. Everyone had left me. But I had still been unable to find the precious person who had gone missing. And so I had gotten the help of an organization. They had confidently said they could do it. It had almost seemed they must have had something to do with his disappearance, but that was fine. Anything was fine as long as I was able to make my way closer to him.

And so I read through the rules of the attraction.

First, register a two digit number in this machine.

Afterwards, both participants shall try to search out the other’s number. That is all this attraction is.

“...”

I used my index finger to enter a number into a panel with the numbers 0 to 9 lined up like on a calculator. I was entrusting my fate to this number.

I could not see my opponent’s face.

I had no idea what bait my opponent had been lured here with.

It was a bit like we were facing each other across a table, but a thick wall covered everything but our hands much like the reception area at a bank or post office. The main difference from those places was that this wall was solid instead of transparent.

...What a pain.

In a one-on-one game, it had to come down to psychological warfare. For that reason, not being able to see my opponent’s expression or eye movements was a disadvantage.

Several cards lay on the table.

A quick count numbered them at about 20 and they all had “questions” on them.

“Divisible by 1.”

“Divisible by 2.”

“Divisible by 3.”

“Divisible by 4.”

“Divisible by 5.”

“Divisible by 6.”

“Divisible by 7.”

“Divisible by 8.”

“Divisible by 9.”

“Even.”

“Larger than 50.”

“The sum of Digit 1 and Digit 2 is larger than 15.”

“The product of Digit 1 and Digit 2 is larger than 25.”

“The difference of Digit 1 and Digit 2 is negative.”

“The quotient of Digit 1 and Digit 2 is a whole number.”

“Digit 1 and Digit 2 are more than 5 apart.”

“Reversing Digit 1 and Digit 2 produces a larger number.”

“The square of the number is odd.”

“The square of the number is over 2000.”

“Thrice the number is over 50.”

I knew there were methods of finding out what number someone had thought of, but I did not know the trick to them. Was it possible with just these cards or were the questions limited to ensure I had to guess?

The smiling bunny girl who was circling around the table while ignoring the partition said, “When you ask a question, slide the question card through the slit at the bottom of the partition. You must give an accurate answer to the question. We will be double-checking for you, so no cheating, okay?”

We were forbidden to talk outside of the bare minimum needed to answer the questions.

It was still possible there was a way of reading my opponent’s mental state from how they gave their answer, though.

The bunny girl then added, “Once one player uses a card, neither player may use it. In other words, if one of you plays ‘even’, neither of you can play ‘even’ after that.”

“...”

“You will take turns using cards. Once you know your opponent’s number, press this button. The one who answers first is the winner, but you automatically lose if you give an incorrect number. That means you will be killed, so be careful.”

“One question.”

“Yes, what is it?”

“If we take turns, won’t the player who goes first have an advantage? They get the first shot at the cards that can’t be used again and they get the information needed to find the number sooner.”

“But using a combo of multiple cards can be used to determine the number. The second player may have the most useful cards sealed, but they have the chance of determining their opponent’s combo and sealing it. And about the ultimate answer, we will also give the second player an opportunity to answer if the first player answers correctly. If you are both correct, the round ends in a draw. You will then enter a new number and begin the second round.”

“...”

The bunny girl casually performed a coin toss to determine the playing order.

“Okay, Saiki-san. You go first!”

I was first.

I glanced over the cards lined up on the table. At first, it seemed all the different options were convenient, but that was not the case. There were a few obvious trap cards that gave the same information as another card.

“Divisible by 2.”

“Even.”

“The square of the number is odd.”

Those three all meant the same thing.

“Divisible by 2.”

“Divisible by 4.”

“Divisible by 6.”

“Divisible by 8.”

Those four...

“Divisible by 3.”

“Divisible by 6.”

“Divisible by 9.”

...and those three would be best used when the number was small. Of course, they could be used in other ways depending on the situation.

But there was one question I needed to ask first.

One important question card would narrow down a lot of numbers from the possibilities for the random 2 digit number.

And...

As a preemptive strike, I wanted to keep my opponent from using that card.

“This is the one,” I muttered as I slipped the card through the slit in the partition to ask my opponent their first question.

The card said, “Larger than 50.”

The answer I received was, “No.”

That meant my opponent’s number was less than 50.

I knew exactly which card I wanted to use next, but...

A card slid toward me through the slit.

I read it.

“Even.”

“...No.”

So that’s what you’re going for, hm? How naïve.

As previously explained, a few cards explained the same thing in different words.

I grabbed one of those and pushed it through the slit.

“Divisible by 2.”

“Yes.”

With that, I had narrowed down the 100 possibilities to about a quarter of that.

In other words...

2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, or 48.

But accurately narrowing down the candidates from here on would be difficult.

As I brought that string of numbers to mind, a card slid toward me from the other side of the table.

“Divisible by 3.”

“...? No, but...”

I frowned at that question card, but still answered.

He just asked me if it was even or odd, so why?

“Ah!?”

“Saiki-san, please do not speak outside of answering the questions.”

The bunny girl lightly rebuked me, but I had other things to worry about.

Not good.

Not good!!

I had answered no to if it was even and no to if it was divisible by 3.

What that told my opponent was obvious.

I had revealed that my number was a fairly special example of an odd number.

If he asked if it was divisible by 5 and if it was divisible by 7, he would narrow it down quite a bit. Even if I answered no both times, he would find out I had chosen an extremely special number that was not divisible by any whole number!

Should I use up either “divisible by 5” or “divisible by 7” to seal his combo?

But neither of those cards would help me determine what number my opponent had chosen. I would waste a turn. The first person to answer correctly won, so it was best to find my opponent’s number with as few question cards as possible.

“Saiki-san? Hurry, hurry.”

Kh.

Should I go the high risk, high return route by finding his number as quickly as possible?

Or should I go the low risk, low return route by protecting my number?

After thinking for a bit, I slid a card through the slit.

“Divisible by 5.”

“Yes.”

...Huh?

I had been too afraid to gamble and decided to waste a turn, but that had actually narrowed it down quite a bit.

After all, the only possible numbers left were...

10, 20, 30, and 40.

Those were the only four.

In that case, I could determine his number with two cards that each narrowed those four down by half.

But what would my opponent do in response?

After being this cornered, he would likely use one of the really good question cards I was thinking of. But...

“Divisible by 7.”

“Eh...?” 𝘧𝓇𝒆𝗲𝓌𝙚𝙗𝓷o𝘷𝒆𝘭.𝐜𝚘𝒎

I was caught off guard.

But...eh?

It was true that was one strategy, but...

“Saiki-san, please give your answer.”

“N-no.”

I answered honestly, but I was dissatisfied.

I could only think my opponent’s strategy was to determine my number as quickly as possible to end the game before his unfavorable situation could work against him.

But could he risk his life on that?

I could end this game by determining his number out of four options.

Normally, he would be working to seal any possible combos of mine.

I could not tell what my opponent was thinking.

I felt very uneasy. I was no longer sure the situation was developing as nicely as I thought it was.

I glanced over the cards I had left and sent the one I needed through the slit.

The question was...

“Divisible by 4.”

“Yes.”

That left only 20 or 40 as options for my opponent’s number.

But...

He had answered almost immediately. He had not hesitated. And the next card slid towards me was...

“The product of Digit 1 and Digit 2 is larger than 25.”

He’s still going on the attack!?

That did not seem to narrow it down quite as much as “divisible by 5” or “divisible by 7”, so his strategy seemed to be showing some cracks. And yet he had still shown no sign of sealing my combo.

“No.”

I answered, but doubt spiraled around within me.

What was going on?

Was my opponent just an idiot who was not thinking at all? Or was he leading me with the thought that I would win?

In other words...

Did I not have my opponent as cornered as I thought I did?

Was it possible I was being led to an incorrect answer?

My fingertips trembled.

Even so, I grabbed a card and sent it through the slit.

“Divisible by 8.”

“Yes.”

It was over.

The answer was 40.

That had to be the answer, but something was still bothering me. What was it? I could think of nothing wrong about my calculations or strategy. I had been led to the correct answer. But I still had a strange uneasiness in my chest.

And it came from my opponent’s lack of hesitation.

It could of course be a bluff, but what point would that serve? Playing even a single card to seal my combo would have forced me to play more cards to find this answer.

“...Wait.”

Wait a second.

Could it be...?

I thought back over the cards I had played up to that point.

“Larger than 50.”

The answer had been no.

“Divisible by 2.”

The answer had been yes.

“Divisible by 5.”

The answer had been yes.

“Divisible by 4.”

The answer had been yes.

“Divisible by 8.”

The answer had been yes.

Nothing seemed strange at first glance, but the sequence of “divisible by X” bothered me. It was divisible by 2, 4, 5, and 8. It was divisible by everything I had asked. A number like that was not too common. More importantly, I doubted someone would normally risk their life on a number like that.

Of the “divided by” series from 1 to 9, the number I had chosen was only divisible by 1.

So there was more to this.

What was the identity of this troubling feeling I had? What was the great trap my opponent had laid?

Was there an answer other than 40?

If he had chosen his number to trap someone calculating out the number via the normal method, there was only one option.

“I’ve got it!!”

I slammed my palm down on the button equipped on the table and a cheap electronic tone sounded.

The bunny girl asked, “Okay, Saiki-san. What number did your opponent choose!?”

This would end it.

I had to choose one of two options.

In the off chance that my opponent had given this no thought at all, I was throwing away the correct answer and running to my own destruction.

But I seriously doubted that was the case.

If he did not have some kind of plan, he would not have showed so little hesitation in his answers.

In that case...

The number chosen by this person I had never seen was...

“Zero!!”

Notes

1. ↑ The narrator uses a feminine first person pronoun.