Ask HN: Why does MM denote millions of dollars? | Hacker News Reader

Ask HN: Why does MM denote millions of dollars?

2 pointsHavoc5 comments

Per SI unit convention a single M indicates mega/millions. A quick Google suggests its related to Roman numerals - but MM in Roman numerals would suggest 2000, not a million. Other Google results indicate that M stands for thousands, not millions and so 1000x1000. It seems unnecessarily confusing to me.

As far as I can tell this convention is used mainly in the startup/VC scene, so I'm hoping someone here has a conclusive answer as to why MM is used.

  M = 1000 in Roman Numerals
  MM = 1000 1000s, or, 1 million

Years ago, I think it was G. Gordon Liddy that used to refer to billions in a similar manner. i.e. 10 billion dollars was spoken as 10 thousand million so people grasped the enormity of the number.

As a Latinist, this makes me cringe. Roman numerals are added, not multiplied. MM = 2000.

Not saying that this isn't the root; just that it is deeply dissatisfying.

This forum details the answer quite well: http://forum.wordreference.com/showthread.php?t=460147

I don't quite follow. That thread contain quite a few opinions on the matter & none seem particularly conclusive to me. Is there one in particular that you feel details the answer?

It's much easier to read when scrawled on a napkin and avoids the thousand/million ambiguity. 30MM is 30 million, 3BB is 3 billion. I learned it from a business professor.

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