[StavrosK]

This is offtopic, but what's MM? What's the second M for?

[jcsalterego]

M = 1000 in Roman numerals, but the confusing bit is not reading them like Roman numerals (2000) but rather interpreting them as one thousand thousands, or one million.

[StavrosK]

Hmm, so who uses this? How is it better than just saying $3M?

[jbarham]

MM is the standard abbreviation for million in the financial world. "The great thing about standards is that there are so many to choose from."

[marclove]

This came up in a thread a while back (http://news.ycombinator.com/item?id=1483667). Bottom line is that "MM" comes from the banking/finance world. In banking, $3M actually means $3,000 and $3MM means $3,000,000.

[StavrosK]

I see, thank you. I prefer the SI, kilodollars, megadollars, etc.