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Vol 01 Chapter 09: Arithmetic

「Hmm…」

「What’s the matter, Tetra?」

For some reason, Tetra-chan was sniffing me. Did I eat something smelly yesterday?

「There’s a woman’s scent on you.」

Really? Her nose is too good.

「Actually, last night…」

When I told Tetra-chan about what happened last night, she frowned.

「That’s suspicious. That woman is definitely dangerous. You shouldn’t get close to her.」

「Is that so? I thought she was suspicious too, but she didn’t seem dangerous at all.」

In fact, she seemed quite off guard. I could have easily overpowered her. Not that I would.

「It’s a woman’s intuition.」

「That’s the reason?」

In my experience, a woman’s intuition has never been accurate. But in this world of curses and blessings, maybe there’s something like a sixth sense. Perhaps a woman’s intuition might be accurate… maybe.

「I’ll be cautious, just in case.」

「That’s not enough. I’m coming with you.」

「You’re the one who said it’s dangerous, Tetra. In case something happens, I can deal with it better alone, you don’t need to come.」

Actually, I know the forest better since I walk through it every day. Recently, my physical abilities have improved, and I’ve gotten much faster.

If I’m alone, escaping is easy. But if Tetra is there, I might have to carry her and run in the worst case.

「Uh… well, I guess I can’t then.」

Tetra backed down easily.

That is a relief. She’s very reasonable. If she thinks what I’m saying makes sense, she’ll back down right away. But if she thinks I’m wrong, she’ll voice her opinion.

If it were Ron and Roswald, they’d be stubborn and whiny. On the other hand, Gram and Soyon never oppose my decisions, which can be worrying.

It’s time for the children to start developing the ability to think for themselves. The key is to cultivate logical thinking.

To train logical thinking…

Maybe I should teach them that. It’s not necessary right now, but it will undoubtedly be useful in the future. It shouldn’t be a waste of time.

Now, how should I teach it…

◇

「First, take a look at this.」

I wrote numbers on the ground in Kirisian, a language from a different region. I used a foreign language because the language of this area doesn’t have a written form.

「Read them in order, Ron.」

「Uh, one, two, three, four, five, six, seven, eight, nine, ten.」

「Correct.」

「I can read that much, at least!」

Ron said, looking dissatisfied.

Well, I had to make sure.

It’s easy to learn numbers, even in a foreign language. Plus, we have Tetra, who is a great teacher, so I’m not surprised.

I continue writing on the ground:

ἕν、δύο、τρεῖς、τέτταρες、πέντε、ἕξ、ἑπτά、ὀκτώ、ἐννέα、δέκα

0 1 2 3 4 5 6 7 8 9 10

「What’s that?」

「The numbers below are from my homeland. The top ones are Kirisian numbers. I want you all to remember the numbers below.」

「Why do we have to do such a troublesome thing…」

The children’s faces clearly showed their dissatisfaction. They only just managed to learn the numbers Tetra taught them recently, and now they wondered why they have to do this.

「Because the numbers from my homeland are easier to use. In my homeland, there are many countries, and each has its own set of numbers. But these numbers — Arabic numerals — are used worldwide. They are used worldwide because they’re much easier to use.」

Arabic numerals are very practical.

Although Europe has surpassed the Middle East in science and technology in modern times, during the medieval period, the center of science was the Islamic world. There are various reasons, but one undeniable factor is the Arabic numerals. Incidentally, the origin of Arabic numerals is India.

「Wow.」

Most of the children seemed to understand, but their expressions still showed skepticism.

They might not grasp the concept of different countries having different languages. For them, the world is as big as their village and the city-state it belongs to. In terms of Japan, it’s like a prefecture or at most a region. They’ve never had the chance to encounter a “foreign language”.

「What is this empty circle at the bottom?」

「That’s the number zero. It represents nothing.」

「There is a number for nothing?」

That was the question I was waiting for.

There is no year zero in the AD calendar. It starts from year one. Isn’t that strange? Due to this, people often mistakenly think the first century goes from the 101st to the 200th year. Why is it so complicated? The reason is simple: when the AD calendar was created, the concept of zero didn’t exist in Europe.

「Nothing is nothing, but it’s inconvenient not being able to define it. For example, how many leaves are here?」

「One.」

「And how many are here?」

I covered the leaf.

「None.」

「That’s zero.」

Question marks seemed to appear on the children’s faces.

「The numbers start from one. I don’t see what the problem is. Nothing is nothing.」

「Right… Let’s say this leaf is one. How many are now?」

I tore the leaf in half, set one part aside, and held the remaining half for the children to see.

「One.」

「No, it’s not. The complete form of the leaf we had earlier is one, right? Both halves together make one. So, this is half of one. We call this one-half, or 0.5. Understand?」

「??????????」

Damn, this is going to be tough. For modern Japanese people, zero being the start of numbers is common sense, so it’s not that strange. But it’s different for these kids.

「Let’s try this.」

I drew a number line on the ground.

「This mark at the beginning is zero. Next comes one. So what’s between zero and one?」

「The start is one, right?」

「Space between numbers?」

「Half of one is another one and one, I think!!」

「That basically means two, doesn’t it?」

「Does it increase when you halve it?」

Aaaargh!!!!

「Do you not understand?」

Maybe my way of teaching is bad? I asked Tetra, who I thought was the smartest among them.

「I kind of get it, but also don’t… So you mean to say that numbers aren’t just separate points, but more like a continuous line?」

Um… probably, yes. I’ve never thought about it that deeply!!

But Tetra’s comment seemed to clear up some confusion for a few of the kids. As expected from Tetra.

「I don’t get it.」

「Completely lost.」

Roswald and Ron tilted their heads even more. It seems they got even more confused by Tetra’s explanation.

In the end, the lesson concluded today with just getting everyone to grasp the concept of zero.

This is going to be hard…

◇

A month has passed since I started teaching arithmetic. The children absorbed the lessons like sponges soaking up water, and even the slowest learners have now mastered single-digit subtraction. Tetra, the quickest learner, is already proficient in three-digit addition and subtraction (in other words, column arithmetic). In fact, she seemed to have some prior arithmetic knowledge.

Now that there’s a growing disparity in proficiency levels, it’s become difficult for me to teach them all by myself. So, I’ve started having the children who understand the concepts teach those who are struggling. Teaching others requires a true understanding of the material, and there’s no more effective way to review than to teach someone else.

However, Tetra seemed dissatisfied. Her expression clearly conveyed her reluctance to continue with two-digit addition.

But I can only be in one place at a time. Besides, ten moderately intelligent people can be far more useful than one extremely intelligent person.

Still, emotions are not logical…

「I’ve finished. Check if it’s correct.」

「Okay, let’s see…」

Outside of class hours, in our spare time, I decided to teach Tetra mathematics.

When I said it would be unfair to others, she argued,

「It’s actually more unfair to only have me teach, stopping me from learning anything new. Besides, I’ve been teaching you language, so it’s only fair you accommodate me a little in this.」

Her arguments were sound, so I began teaching her.

「All questions are correct. Looks like you’ve mastered three-digit addition and subtraction. Ready to move on to the next topic?」

「Next is four digits?」

「No, three and four digits are basically the same. Let’s start multiplication.」

It’s still remarkable that in just one month, we’re moving on to multiplication. We are skipping areas like units of measurement and the like, but the speed of acquisition is extraordinary.

It must be a combination of personal motivation and ability.

「First, memorize these.」

「What are these?」

「Memorization cards.」

I handed Tetra cards with the multiplication table written on them. Calling them cards might be a stretch; they’re actually made of wooden boards and quite large. They were difficult to make.

「It’s tedious… Can’t we just do the calculations with addition?」

「It takes longer that way. Memorizing is faster.」

Honestly, I do most single-digit arithmetic by memory now. Probably as a child, I used my hands for calculations, but now I can answer instantaneously. It’s thanks to solving similar problems hundreds of times.

「Once you memorize the multiplication table, you’re almost done with multiplication. Division is similar to multiplication, so it’s easy. You’ll remember it quickly.」

Once this is done, she will have mastered basic arithmetic. With basic arithmetic skills, she should be able to get by in her daily life.

Next will be calculating length, area, volume, as well as speed and distance.

Honestly, teaching this is more troublesome than basic arithmetic. I don’t know the units of length or weight in this world, after all. I think that the value of the measurements was related to the longitude of the Earth or something like that, but I’m not even sure if this world is spherical. Maybe there’s some sort of magical power here substituting for gravity.

「Hey, Almus.」

「Hm? What is it?」

I still feel a bit strange being called Almus. Usually, I’m referred to as ‘Nii-san’ or ‘Leader’. Only Tetra and Julia call me Almus.

「Did everyone in your homeland do this?」

「Well, yes… Children around Tetra’s age all could. Everyone starts at around seven, and normally, it takes about two years to memorize up to multiplication, so Tetra is actually really talented.」

「Does everyone learn it?」

「Yes. In my country, there’s something called compulsory education, which is considered a right of the citizens.」

By the way, children have the right to receive education, but it’s not their obligation. It’s the parents who are obliged to provide education.

「Why do that? Wouldn’t it be better for the rich to monopolize the knowledge?」

「True, that might be good for the privileged class. But in my world, there are many countries besides mine, all competing with each other. If you monopolize knowledge, you can’t gather talented people, right? Then you’d lose in the competition.」

Especially in a capitalist society, education is a lifeline. And for democracy to work, the populace can’t be ignorant.

「It sounds tough.」

「Yeah, it is…」

In a way, you could say that it’s hard. This world isn’t as fiercely competitive, possibly because agriculture is the main occupation of the people here. No matter how much effort you invest in agriculture, which is heavily reliant on nature, the returns are relatively small. The lives of the people of this world could be considered poor or in line with nature depending on your views.

To the Japanese, people in this world might seem too relaxed. To this world people, the Japanese might appear too busy. Well, the hard work of the Japanese is known worldwide. Although working hard is not always related to efficiency…

Lately, there are a lot of people in Japan who live to work instead of working to live.

I’ve digressed and ended up grumbling.

「By the way, Almus?」

「What is it?」

「When will you be able to speak correctly?」

「It might be hard for you to understand, but learning a foreign language is incredibly difficult.」

In contrast with the children, I’m struggling to learn the language. Still, I’m learning faster than I did with English.

「Why don’t you try living without using the [Blessing of Language]?」

「Hmm, but then I wouldn’t be able to teach you math.」

「Guess we should keep it as is.」

「Haha.」

Without thinking, I stroked Tetra’s hair. I thought she might dislike it and was about to pull away, but she snuggled closer.

This is nice. Her hair is so soft and silky. It’s amazing that her hair is this soft even without soap.

Sigh… I really need to work harder.

I sighed deeply.