Journal Alioth's Journal: Why MM? 1
Here's something that's been bugging me for ages.
Why do rich people and financial types write million as MM, for example, $1MM?
Someone told me once "well, the Roman numeral for thousand is M, so MM is a thousand thousand". That explanation, however, is not right. MM in Roman numerals means 2000. Million, in Roman numerals, is a single M with a bar on top. It also doesn't make sense to use the Arabic 1 plus the Roman numerals for a number.
As far as I can tell, when people write $1MM instead of $1M, it basically means "and I know lots about money and have a lot of it".
Different conventions probably (Score:2)
Money is apparently not standardized by SI.
The financial people also seem to like to use the single quote for "thousand" and B or b for "billion" I've noticed. I've also seen lower-case variants m or mm for "million" making it look more like 1/1000, millimeters or meters.
Makes for hard reading when being used to SI prefixes, where case differences of the letter M can mean a 10^9 difference of the value.