Mmmm...
　What's up?　Tetra.
　Tetra smells my body for some reason.
　Did I eat something stinky yesterday?

　I smell a woman.
　Oh, man.
　Your nose is too good.

　Actually, yesterday...
　When I told Tetra-chan about last night, she scowled.

　''I doubt it. That woman is definitely dangerous. Don't go near her.
　Really?　I thought it was fishy, too, but it didn't look dangerous at all.
　She was rather unguarded.
　I could have pushed her down with room to spare. I'm not going to do it.

　A girl's intuition.
　What is that?

　At least in my experience, a woman's intuition has never been right.

　However, this world is a world where there are curses and blessings.
　Maybe there is at least the news of a bug. A woman's intuition may also be right.....

　Then I'll just be on the lookout for you.
　It's not enough. I'll go with you.
　You said it was dangerous, Tetra. I'm lighter on my own and you don't have to come.
　In fact, the ground advantage is in me walking in the woods every day.
　My feet are much faster these days, thanks to my improved physical abilities.

　If you're on your own, it's easy to escape.
　But with Tetra around, the worst that can happen is that you'll have to escape with Tetra on your back.

　''Ugh... then it can't be helped.
　Easily, Tetra pulled back.
　Tetra is a good listener, which helps. If he thinks what I'm saying is right, he immediately backs off. On the other hand, if he thinks it's not right, he'll give me his opinion.

　If this is Ron and Roseward, they don't back down easily and get upset.
　On the other hand, Gram and So Yeon don't disagree with me at all, which worries me.

　It's time for the kids to learn to think for themselves.
　What's important is the ability to think logically.

　How to train them to think logically....

　I could teach you that one.
　We don't need it now, but it will definitely help us in the future.
　It shouldn't be a waste of time.

　Now, how do we teach it....


_______________________________________________________________.


　Look at this first.
　I write numbers on the ground in Cilician, a language that is not from this part of the world. The reason why I write in a foreign language is because this region does not have its own script.

　'Read them in order. Ron.
　Uh, one, two, three, four, five, six, seven, eight, nine, ten.
　You're right.
　I can read at least that much.
　Ron complained.
　No, because you won't know until you check.

　Well, even though it's a foreign language, it's easy to learn numbers.　
　I have an excellent teacher (Tetra).

　I continued to write on the ground, "One, two, three, four, four.

　　　　　　　　One, two, three, three, four, five, six, seven, eight, nine, ten.
　　　0 1 2 3 4 5 6 7 8 9 10

　What?
　The numbers on the bottom are my hometown numbers. The top one is Cilicia's number. I want you guys to remember the numbers on the bottom.
　Why bother with all that...
　The kids look overtly frustrated.
　They're not happy about why they have to do this, even though they've only recently learned them from Tetra.

　'It's because the numbers in my hometown are more useful. There are many countries in my home country, and every country has its own numbers. But this number - the Arabic numeral - is the only one that works all over the world, because it's easier to use. That's how easy it is to use.

　Arabic numbers are very reasonable.

　Today, Europe is more technologically advanced than the Middle East, but in the Middle Ages, the center of science was the Middle East, the Islamic world.
　There are many reasons for this, but Arabic numerals are definitely a major factor.
　For what it's worth, Arabic numerals originated in India.

　Heh.

　Most of the children have a look of "I'll agree with you, but I don't know what it means". Maybe these kids don't understand how different languages are used in different countries in the first place.
　For them, the world is just their village and the city-state to which it belongs. In Japan, it's like a prefecture, or at the most, a region. They don't have any opportunities to come into contact with 'foreign languages'.

　What's the circle under this blank space?　
　The number zero. It's a number that means nothing.
　Is it there for nothing?
　Tetra asked.
　Yes, I've been waiting for that question.

　There is no year zero in the Western calendar. The first one is a year.
　And don't you think it's strange?
　Because of this, people often mistake the years 101-200 AD for a century.　
　Why is it so troublesome?
　The reason is simple. The reason is simple: when the calendar was created, the concept of zero did not exist in Europe.

　'Nothing is nothing, but it would be inconvenient if we didn't define it. For example, here's a leaf. How many?
　One piece.
　So how many cards are these?
　I hide the leaves.

　...no.
　It's called zero.
　In the faces of children? comes to mind.

　'The number starts with one. I don't know what's troubling me. Nothing is nothing.
　'Well let's take one of these leaves then. How many leaves is this one?
　I shred the leaf in half, throwing one away and showing everyone the half-finished leaf.

　'One,'
　'No. That was one complete leaf from earlier, right?　Both of these halves combined are one piece. That is, one half of a piece. This is called a half, or zero-five. See?
　?

　Shit, that's going to be a pain in the ass. It's common knowledge that zero is the beginning of a number for modern Japanese, so it's not that different.
　But it's different for these kids.

　Then I'll do it this way.
　I draw a few straight lines on the ground.

　"The memory at the beginning of this one is zero. After this is one. Then what's between zero and one?
　It's a good start, isn't it?
　The numbers?
　'I think half of one is another one and one!
　That's two, in a nutshell.　
　Does it increase when you cut it in half?

　d*mn it!!!!

　Hey, don't you get it?
　I knew I wasn't good at teaching.
　I ask Tetra, who is probably the smartest of them all.
　

　Um ... maybe so.
　I never thought about it that hard!

　But now Tetra's remarks have cleared the faces of some of the kids. That's Tetra, indeed.

　'I don't know what that means,'
　No.
　Rosward and Ron nodded their heads further. They got even more confused by Tetra's explanation.


　In the end, today's class ended with just getting everyone to agree on the concept of zero.

　I can't imagine what's ahead.......

_______________________________________________________________.


　It had been a quick month since I taught math.
　The children learned like a sponge absorbs water, and even the slowest child could master single digit subtraction.
　By the way, Tetra is the fastest learner, and she can already do three-digit addition and subtraction (in short, penmanship).
　Or rather, he seems to be able to calculate to some extent to begin with.

　It's getting difficult for me to teach him on my own, as his proficiency level is starting to vary widely.
　So I started to let the kids who can do it teach the kids who can't.
　You have to really understand what you're doing in order to teach others. There is no more effective review than teaching someone.

　But Tetra was not happy. I don't want to do double-digit addition now," she said.

　But I only have one body.
　And ten people with a little bit of brains are much more useful than one person with a lot of brains.

　However, it seems that dissatisfied things are dissatisfying things....

　There you go. Check it out.
　Copy that. Uh....
　I decided to teach math to Tetra in my free time, outside of class time.

　When I told her not to do it because it would be unfair, she said, "It's unfair to have her teach me all the time and not teach me a little bit, and since I'm teaching you the language, you need to be this flexible".
　I understood, so I am teaching like this.

　I thought I understood, so I am teaching in this way. I think you got all the answers correct, and for the time being, you can add and subtract three digits perfectly. Well, let's move on to the next one.
　Four figures next?
　'No, three or four digits won't make a difference. Now multiply.
　But still, that's an unusual rate of multiplication in a month or something.
　Even though I'm skipping units of length and other fields, that's still quite a speedy learning curve.

　Is it the difference between his motivation and ability?

　"Memorize this for the time being.
　What is this?
　"Memorization cards.
　I give Tetra a card with the nine nines written on it.
　It's a card, but it's made of a wooden board, so it's pretty big. It was hard to make.

　'It's so tedious you can just add it up as normal.
　It takes time. It's faster to memorize.
　Honestly, I've memorized most of the four arithmetic operations between single digits.

　I probably used to work hard with both hands when I was little, but now I can answer the questions in an instant.
　Well, it's because I kept solving the same kind of problems hundreds of times.

　But once you learn the nine, it's almost like you're done with multiplication. Multiplication is just as easy as multiplication. It's easy to learn.
　Once this is done, the four arithmetic operations are done.
　As long as you can do four arithmetic operations, you will have no trouble in your daily life.

　After the four arithmetic operations, it will be time to calculate length, area, volume, and speed and distance.

　Honestly, this is more complicated to teach than the four arithmetic operations. I don't know the units of length or weight in this world.
　As I recall, there is some definition of what the length of the earth is or something like that, but it's also a mystery whether this world is a sphere in the first place. Maybe magical power exists instead of gravity.

　'Hey, Alms.'
　Hmm?　What?
　I still feel a little uncomfortable with being called Alms. It's because I'm usually called either brother or leader. The only people who call me Alms are Tetra and Yulia.

　'Did they all make it back home?'
　'Well yeah all the kids are about Tetra's age. Well they all start when they're seven and it usually takes two years to learn to multiply, so I think Tetra's better at it.
　Do people learn to do that?
　Yeah. In my country, we have this thing called compulsory education, and it's considered a right of the people.
　By the way, what the child has is the right to education, not the obligation. It's the parents who have an obligation to make sure they get an education.

　'Why would you do that?　You'd be better off being rich and having a monopoly on knowledge.
　'Sure, that might be good for the privileged. But there are many more countries in my world than just mine. Countries are competing with each other. If you monopolize the knowledge, you won't be able to attract the best people, right?　If you do, you'll lose the competition.
　Education is a lifeline, especially for a capitalist society.
　And in a democracy, you can't talk about it if the people are stupid.

　'It's hard work, isn't it?'
　'Well...'
　You can certainly see it that way.
　The competition is not that fierce in this world. It's probably because no matter how hard you work, there is a lot of point where farming depends on nature. There is little return on your hard work.
　Whether one considers this to be poor or quiet depends on the person.

　To a Japanese person, people in this world would seem to be too laid back. To people in this world, the Japanese seem to be in too much of a hurry.
　.........and the Japanese are one of the most hurried people in the world.
　They work hard, but not efficiently.

　It's not that they are in a hurry to live, it's that there are too many people who are living in a hurry to live.

　I digress. I'm getting off track.

　"By the way, though, Alms.
　What?
　When are you going to master the language?
　You may not know this, but it's extremely difficult to learn another language.
　I had a hard time learning it, as opposed to the kids.

　Still, it was a lot faster than learning English.

　"Why don't you just cut off your language blessings for a while?　
　Hmm, but that doesn't mean I can't teach you math, does it?
　I'm going to have to go without it.
　Ha, ha.
　I couldn't help but stroke Tetra's hair.
　For a moment I thought she wouldn't like it, and I tried to let go of her hand, but she snuggled up to me.

　This is good.
　It's nice and silky to the touch.
　How can my hair be so soft without soap?

　'Huh I'll have to work on that.
　I sighed.