Pinned toot

Hi! I'm a maths student at Helsinki University. For the past year or so I've been writing a popular (not as in visitors) maths blog,, in Finnish. In addition to human languages (FIN/ENG/SWE/FRE) I respond to quite a few computer ones (esp. C#).

Interested in seeing if toots > tweets!

- a microSD card weighs somewhere around 0.4g
- the highest capacity microSD that's easily available is 256GB
- a trebuchet can throw a 90kg projectile over 300m

90kg worth of microSD cards is 225,000 of them

Therefore a trebuchet can throw 57.6PB of data over 300m

This would have the highest throughput of any telecommunications network ever created

Worried about the dominance of big instances? No, really, this is quite natural.

As an emergent and self-governing system, it could be expected that the size distribution of #Mastodon instances roughly follows Zipf's law.

Does it?

At first you see the top 6 instances, and then the rest. But on a log-log scale the size distribution is close to a straight line, which would be expected from an emergent system.



stupid source control pun Show more

I deleted about 5000 lines of code today. It felt so good.

Knowing mental arithmetic tricks saved me from several minutes of debugging today. A supposedly integer algorithm was producing results like 17.428571, just due to me dividing a circle not in 2, 3, 4, 5, 6, 8, or 9 parts!

It turns out my freshman year in was equivalent to 11 centimetres of paper. (I used ebooks for statistics.)

@andrewt From Gareth McCaughan.

The average number of ways to express numbers from 1 to N
as sums of two squares


(total number of ways to express numbers from 1 to N as \(X^2+Y^2\) )/N


(total number of (x,y) for which \( 0 < x^2+y^2<=N \) )/N


(total number of (x,y) inside the circle
\( X^2+Y^2=N \), minus 1)/N


(area inside the circle \( X^2+Y^2=N\) + O(N) ) /N


(area inside the circle \( X^2+Y^2=\sqrt{N}^2 \), +O(N)) /N

= \( \pi\sqrt{N}^2+O(N))/N \)

= \( \pi+O(1/N) \)

Just finished Jordan Ellenberg's How Not to Be Wrong. Good mix of theory + rhetoric, touches on some hot issues, and imparts several important moral lessons.

A little spoilery: the book indeed suggests ways to not be wrong using mathematical lenses, but cleverly doesn't promise "ways to be right" 😉

@JordiGH In fact it's based on a lovely result from the 1930's, way before the probability arguments become common in combinatorics.

CC: @petrilaarne

I quite liked @ColinTheMathmo’s entry to : a simple, initially counterintuitive result that becomes intuitively obvious after a quick think! I wonder how many totally different ways there are to prove it.

If you haven’t yet, go read about it and beautiful Penrose tilings:

I’m amazed that I managed full six weeks before messing up my repository at work.

I'm running a four-round instant knock-out tournament throughout the month of July to basically squeeze a load of fun maths out of my friends. Let's see if we can make it all come together! Voting starts on the 1st of July.

I’ve now updated the original post with a solution. Hoping that we found the same one!

being an applied mathematician means praying to every religious figure that your code converges

Correction: 18D should read ”Each digit is the last digit of twice the preceding digit”. Thanks @christianp for spotting this! (And very ace to solve a puzzle with an error in it 😎)


When designing a user interface, imagine some old woman using it, say Margaret Hamilton, and she's clicking your app's buttons and saying to you, as old people do,

"Young whippersnapper, when I was your age, I sent 24 people to the ACTUAL MOON with my software in 4K of RAM and here I am clicking your button and it takes ten seconds to load a 50 megabyte video ad and then it crashes

I'm not even ANGRY with you, I'm just disappointed."

If you fancy a bit bigger but not too difficult , I just published a on my blog! I promise it’s much easier than the Magazine one.

It is also very humbling to work in a team of so many PhD’s. My interpretation of ”fun algorithm work” is pretty lame compared to what they do! Still, very encouraging to see how much I already can do.

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A Mastodon instance for maths people. The kind of people who make \(\pi z^2 \times a\) jokes.

Use \( and \) for inline LaTeX, and \[ and \] for display mode.