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fletchowns

Why do I always see people using lowercase "mm" to abbreviate million? That doesn't make any sense to me.

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Doubling to indicate a plural initialism, like "pp 3-7" for "pages 3-7" or "EE. UU." for "Estados Unidos".

Roman number M = 1 thousand

1 thousand 1 thousands = 1 million

Exactly, capital M

But, then that would be 150 * 2000 = 300,000.

Exactly. 1 million in Roman numerals is M with a bar over the top of it.

Yes. If we're talking Roman numerals, MM would be 2000, just like XX is 20 -- not 100. This notation makes no sense to me either.

I've always seen k used to represent one thousand in dollar amounts, so I've never interpreted M as being a Roman numeral but simply as standing for "million."

Disclaimer: I've been in the US my whole life.

We don't use Roman numerals for thousands, why should we do so for millions? The right way is obviously using metric prefixes, so 1k$, 1M$ and 1G$.

And don't forget that 'cents' is short for 'centidollars'.

Is there a special reason the 'k' is lowercase?

Well, M for mega is capitalized since m is already used by milli. And all of the SI prefixes larger than mega are also capital, I guess to denote that they're large...

All of the SI prefixes k and below are lowercase.

m is 1,000. mm is m * m or 1000 * 1000, which is 1,000,000

MM, sure. mm, however, is millimeters.

its done in finance sometimes and the thought behind it is m = 1000, so multiply 1000 by 1000 and you get 1,000,000.

Personally I hate that notation and use capital M whenever given the opportunity. I feel like it used to show superiority or present another barrier to people outside of finance looking in.

a millimeter is = to 1000 micrometers.

150 mega-megadollars??

Mille is Latin for one thousand. It's still heavily used in French and perhaps as much in Italian.

I have literally only ever seen this on HN.

(from the UK where m = million)

you know how a few years back it became popular to say "kk" in online games instead of "k" or "okay"

I suspect people use MM/mm for the same reason, some guy just made a typo one day and it caught on.

kk=okay, cool

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