IJBM: I missed Cirno Day

glennmagusharvey

oops

Stormtroper

I considered posting about it here, but didn't. oops.

If it helps matters, Cirno Day is not what it used to be. You see a couple dozen congratulatory pictures and maybe a video or two, but that's it.

On related news, I made the strongest cake:



Edit: On second thought, looking at all that noise/artifacts, this one is probably better, candles notwithstanding:



Oh yeah, original Cirno picture by Karasusou Nano.

glennmagusharvey

How did you get it printed like that?

Naas_Human

I don't think that's a physical IRL cake...?

Stormtroper

It isn't.

Bluesy_Cowgirl

I made one post about it in my thread on HH and that was the extent of my Cirno Day

glennmagusharvey

TYL: you can fool GMH with a low-res, dimly-lit picture of a nonexistent cake.

Stormtroper

I thought the first one had reasonable enough resolution. The second one definitely did, tho.

Anyhows, I just realized I never posted this, courtesy of the TV thread:

glennmagusharvey

NOTE: read right to left.

glennmagusharvey

posted by Saphyr (source: https://danbooru.donmai.us/posts/439608 - warning, possibly NSFW ads)

over 6 years ago

> lily_white said:

> SCIENTIFIC QUESTION:
> If you had Cirno an equation with a 9 in one of the operands, will she write "NaN"? Or will her head explode?
> Inquiring minds would like to know!

I had Keine conduct a few mathematical experiments for me to confirm my own hypothesis; don't ask how I ended up there, but this question stayed fresh in my mind as I entered the village (Reimu later had me leave, but she allowed enough time to conduct my experiment... a rather decent girl when you have enough pocket change on you...):

If the "9" happens to be found in between two other digits, Cirno will remark that the problem has been miswritten. We partly discovered this when asking her to solve the problem 94 + 12 = ___; she said we did something funny with the setup, erased the "9" next to the 4, and placed it on the right-hand side of the 4... (the natural format by which an "x" would go next to a coefficient in an algebraic equation; we later saw that she was absolutely perplexed by setups with "9" in-between two digits, looking at us with eyes that are meant to be cast upon insane people).

We then had her try to solve the equation she had setup: 49 + 12 = ___.

She asked for us to fill in the other side of the equation for her after an awkward pause as she looked upon us with a face that said, "what exactly do you expect me to do with this?"
We displayed the correct answer in decimal for her: 49 + 12 = 61; we were about to call it a day and resume the usual class schedule until Cirno finally started marking the board: 49 = 61 - 12 = 48...

At this point, while we were mindful of the fact that Cirno worked in base 9, we felt the unfortunate need to remark to her that "forty-nine does not equal forty-eight", upon which Cirno looked at us and said in a surprisingly matter-of-fact tone, "of course it doesn't...but what does that have to do with this?", leaving us flustered at our apparent stupidity for a moment as we watched her CONTINUE to work the problem: 9 = 48/4 = 12.

At this point it became clear that the "9" was indeed being treated as a variable in the equation... and Cirno had performed a completely correct subtraction and division in base 9 to do it.

The number would not register as having the same significance to Cirno as the rest of us with consideration of its value in the decimal system to represent a particular quantity. Rather, she'd assume, since the number "9" could technically count as a letter or a symbol of some sort, that "9" is a variable that she must solve for by algebraic or other means.

This is my favorite interpretation of Cirno.

glennmagusharvey

SPOT THE ERROR

Stormtroper

[ The sqrt(9!) should be sqrt(9)! instead.]

mfw this thing is cirnology

glennmagusharvey

I only recently found out about digital roots and I thought it was a load of trivia but apparently it is its own branch of number theory with handy applications.

That pattern that involves the digits 1,2,4,5,7,8 in some order is interesting in that it doesn't just show up for 2 and 5 power digital roots (which kinda makes sense since we're using a base-10 numbering system), but also shows up in imperfect division by 7. (Is that actually because 2+5=7?)

I still hate the name "digital root", though. It implies something opposed to analog and something involving fractional powers. Except it's just adding up the digits over and over again. I'd have called it "digit sum compression".

Stormtroper

If nothing else, that's where the 3, 7 and 11 divisilibity tricks come from.

I had a harder time than I'd like to admit in demonstrating the 1,2,4,8,7,5 thing, although in the end I did.

I've been toying with the idea of doing a master's in applied math, though I have to find out if it's as cool as it seems at a glance.

fourteenwings

inb4 full blown Cirno math cult

Central Avenue

I would buy that clock, even if the aforementioned error would drive me mad every day.