huh, this makes a lot of sense and is kinda cool
so, I was wondering why mahjong tiles use all the standard numerals for digits except five, which uses the "financial" version
backing up a bit, in latin scripts, we tend to write out numbers in full on financial documents like checks to prevent them from being altered. it's very easy to change a 1 to a 7 but much more difficult to change one to seven
but in chinese and languages which use chinese characters, the numerals are the words. with extremely simple numerals it's trivial to change them by adding in extra lines:
一二三四五六七八九
so, there are "financial" versions of the numerals that are much more complicated and can't easily be changed to match each other:
壹貳參肆伍陸柒捌玖
out of these numerals, one stands out as being much more similar to its original: five (五). in particular, it's the same character, but with a "person" radical next to it: 伍
it's also the only character which uses its financial version on mahjong tiles instead of the original
so, it turns out that apparently, this is to ensure it has a different tactile feel from three (三), which differs from five by two lines, assuming that this reddit comment is accurate: https://www.reddit.com/r/ChineseLanguage/comments/16liu0b/why_is_%E4%BC%8D_used_on_mahjong_tiles_instead_of_%E4%BA%94/
since mahjong tiles are small and harder to hold/hide, a lot of people rely on feeling the tiles instead of looking at them to determine which tile they are, and this makes the tiles feel more different. (unlike playing cards, mahjong tiles are pretty much always engraved)
which is a cool case of a game being made more blind-accessible even if it wasn't necessarily the intention originally
@clarfonthey fascinating! Thanks so much for sharing!
@foone@digipres.club@clarfonthey very cool info! Thanks for this.
Very interesting. Similarly, the form of 3 that is flat and pointy on top is known as the "banker's three" because it was employed in finance to prevent it turning into an 8.
@gowin@social.tchncs.deAn interesting factoid I can share in my next mahjong game! 
Love this. Nice topic. Thanks.
This kind of topic is why I love Mastodon. Thanks again!
@clarfonthey how do you think mahjong is blind-accessible? Do people feel every tile on board?
@oreolek @clarfonthey afaik if one is playing mahjong with a blind person, you have to announce your discards and call the tiles in your melds and dora tiles and such, so that the blind player gets all the public information others do
@rnd @oreolek mahjong is also usually pretty good about not forcing people to remember things; every discard is laid out flat for future reference and even discards taken to form melds get arranged so you can tell who discarded the piece that formed it. even if everyone playing were entirely blind the traditional game is played in such a way that you can double-check the state of the game at any point, or at least ask someone to tell you so you aren't awkwardly rubbing around the table