proofed12

Fuh, good thing all the tools inside this bag are battery powered, so you don't have to search for a nearby socket. You doubt you can find one in this ancient village. This calculator only has a messed up screen, typical cheap calculator problem. You can fix it without replacing any parts. You remember how your dad told you to replace the broken parts of the things that's repairable if possible, since those fixable parts won't last long if repaired. If only you were in the family store right now...

*Whoosh!*

A gust of wind blows past your face. What was that? You turn your head to Sanae. She only smiles and waves to you. Frog-Suwako hops from her head to you.

“Come on Nobu, finish that calculator up and explain the device to the man!”

You hear Suwako's voice in your head. You press the power button, and a zero number shows up on it's little screen. Yep, it's working. You return the back and screws on the calculator and give it to-

“Nobu, wait!” Suwako calls again. “You don't expect that normal villager to understand our numerals, do you?”

Uh, he only asked you to fix this calculator. You write to her that it probably better if Sanae does the explaining.

“Okay... Hold on to the calculator. I'll speak to Sanae.” She hops away from you jumps to Sanae. She nods a few times and walks to the calculator owner.

(Why put it on the ground? It's better to just hold on to it for a few moment more.)

“It has been fixed.” She tells him. “Do you know how to operate it?”

“I don't know, Lady. Could you please show me how?”

“Well, he knows! You need to ask him how,” Sanae points to you. Hey, she should know how to operate a calculator too. Why tell the man to ask you?

“I understand.” He bows to you. “Please teach me how to use this object.”

How unnecessary. Sanae could tell him how, why direct him to you? Must be Suwako's influence... What is she thinking? (I changed the wording here a bit. "What's on your mind" is a phrase used when someone seems to be thinking about something, often while looking troubled too.) You write that the calculator is a device that outsiders use to calculate something. You also add that it can only recognize foreign numerals.

“Foreign numeral?”

You point to Sanae. You don't want to write a complete lesson of numerals, it's tiring.

“Foreign numerals is the numbers that's widely used on the outside world!” She pats you on your shoulder. “Could you write number zero until nine with old numbers on their side?”

Fine, as long as she does the teaching. You give your notepad to her after you write those numbers.

“Here! As you can see, this is zero, one, two, three... All the way until nine. You only have to translate the numbers that you want to count into foreign numbers, input it to the calculator using the buttons on it, translate the results into normal numbers, and you got your answer!” Let me show you, ask me any hard calculation that you want to solve.

“Hum... How about four thousand two hundred and fifty two times one hundred and seven?”

*Tak tak tak!*

“four hundred and fifty four thousand, nine hundred and sixty four.”

She shows the result on the calculator to the man. The crowd of people looks amazed and whisper to each other again.

“Miss, I don't see the ten thousands and tens here.”

“They don't have it. You have to look at the order of the numbers, from the right to left. The second number is tens, third is hundreds, fourth is thousands, fifth is ten thousands, and so on! It's much simpler than our numbers!” She gives the calculator to him. “Come on, try it yourself!”

He pushes some buttons and sometimes takes a glance to the writing pad looking for number that he want to input.

“Miss, what's the symbol for subtraction?”

“There! That one is for addition, that is for multiplication, below it is division, and the corner one is equal. You input the first numbers, then the operator that you want to use between that number and the next number that you want to input, then input the next numbers, and press the equal button.”

“One, ten... divided...four.. equals-” He looks confused. “Miss, the result is different.”

“No, it's correct! See the point between the number two and five? That's a decimal point-”

(Why "five ten"? On a calculator it would be 1 0 to write 10, five should never show up at all. I changed it, but you can change it back it you want. I might just have misunderstood his mumblings.)

*WHOOOSH!*

“Hello! Kakashi spirit news reporter here! May I-”

*WHOOOOSH!*

“Hey Nobu, mind giving an intervi-”

Oh gods, it's those paparazzi... The late one hovers on the sky when she realizes her fellow paparazzi got here first.

“I got here first! I have this one!”

“How could you-” She stops talking and flies away. “Okay, you win this time, but don't expect me to let my guard down next time!”

She flies away fast. Well, good, one paparazzi is enough for you. The purple-skirt tengu woman moves to you.

“Ahem, let me try this again...” She sets a smile on her face. “My name is Hatate Himekaidou from Kakashi Spirit news! Do you have time for a little interview for my paper?”

“Miss Himekaidou, I'm sorry, but we're kind of busy here, could you interview other people first? We're kind of busy here.” Sanae speaks to her.

“Of course! Take your time, I won't disturb you! Please call me when you're ready,” She goes to the schoolmarm. “Miss Kamishirasawa Keine, right? I'm from Kakashi Spirit-”

Fuh, at least she doesn't force you to do the interview right away. You can't talk to her either because you writing pad is being used to teach the man now. You better find a paper to make a permanent note for that man. Maybe the schoolteacher has it. You walk to Keine, whose being interviewed now.

“Yes, he did fix it right in front of us- What is it?”

You get her attention when you tap her shoulder. You make a rectangular sign with your hand, and then make a gesture of writing.

“You want to write on a paper?” She guessed, and you nod. “For what purpose? You have your board, right?”

You point to the man, whose still studying on the calculator. Keine sighs and walks into her school.

“Hey, what are you waiting for? Come here.”

Huh? Can't she bring the paper here? You go inside, followed by the white-haired woman.

“Wait... There you go.”

She puts down a paper, a small brush, and an inkstone filled with ink, with an inkstick on it's side, but you don't have to use it since the inkstone is already filled with ink. Man, if only you had carried a pen now... Whatever, this will do. You re-write the arabic and spelled numbers on the paper. You also add the symbols on the calculators and what they do, just in case Sanae didn't cover it all with her lesson. You can feel Keine and the white haired woman looking from the back. The paparazzi also peeks on you from the window.

(Need clarification here, did ancient Japanese used brush or quill to write? And does the tools mentioned is correct?)
(From what I understand, this is correct. They used brushes and ink to write.)

“Are our numbers still being used in the outside world?” The white haired woman asks.

“Well, I've seen those numerals and our numerals co-exist in a book from the outside that I've read before, but our numbers are only being used for describing something in small amounts. For larger amounts, they use the outsiders' numbers instead, probably because, as the Moriya's shrine maiden explained earlier, it's simpler.”

Keine answers her. The white-haired woman nods in acknowledgment. You touch the ink on the paper: it's finally dry. You bow to the teacher as a thanks and walks out to Sanae and the calculator owner.

“...Sorry, he needs that for writing, so-”

You tap the man's shoulder and hands him the paper. You take the writing pad and write that you've written a note for him so he can look to it should he ever forget how to use it, and note that he should treat the object with care, and it will take care of him too. He bows again to you.

“Thank you very much! I'll take care of this object, I promise!”

He walks away with smile, just like the kids who're playing now. Ah, it feels good to help people.

“Ready for an interview now?” The reporter approach Sanae. Yep, time to deal with this paparazzi...

(Anyway:
http://en.wikipedia.org/wiki/Counting_rods
So apparently, Nobu shouldn't even able to checked the kid's homework since they should be still using ancient methods to calculate things.

Or the fact that Gensokyo probably still used old styled writing instead of modern letters.

Damn.)
(Well, considering that things that were advanced 300 years ago are things you learn almost immediately in school today, it shouldn't be too hard for Nobu to understand their homework. Math is math, no matter what tools you use to calculate it.
Also, any of the children who don't go to Keine's school probably can't do more advanced math than simple addition/subtraction without help, i.e. "if I have two rocks and add two more rocks I have four rocks. If I remove one rock I have three." is about the limit of their math knowledge so I don't think the kids in school are learning algebra or something.
Besides Genoskyo is filled with things both old and new, like Aya's camera for example, it's not too strange to think that some things might be more modern than others.
But it's pretty cool that you're thinking about it that much.)