Here's one I always wonder about:

$36.2M; $36.2m; $36.2mm; ?

K, M, B, T, Q

thousand, million, billion, trillion, quadrillion. I'm not a fan of M and MM and MMM, it's much easier to use one letter that is different from the others.

Well. A Billion is ambiguous. In many countries, it's called a Milliard. See: https://en.wikipedia.org/wiki/Long_and_short_scales

I don't think the fact that there are multiple words that represent the same thing means that one is ambiguous. A "billion" is always 10^9, so it's not ambiguous, no?

A "billion" is 10^9 in the short scale and 10^12 in the long scale.

https://en.wikipedia.org/wiki/Long_and_short_scales#Comparis...

It looks like the Long scale is falling into disuse in English speaking contexts from that article. I don't ever think I've ever seen the word "billion" in English refer to 1e+12 .

No, it's the other way around. A billion means one thing in english speaking countries and another in most of the rest of the world. For a frenchman, it's indeed ambiguous -- there, a billion (english) would be a milliard (french), whereas a billion (french) would be a trillion in english. I imagine that is the reason why it's not seen as an abbreviation, in contexts where you want to be accurate.

I think MM is the common way to denote million in finance.

I believe it comes from one thousand (roman numeral M) thousands (roman numeral M) or MM.

Can't upvote this enough. I get the urge to just stop reading whenever I come across "MM". Just use "m" or "M" for millions, for heaven's sake.

It's a finance thing. M = roman numeral for 1,000.

Will i18n ever know peace?