Meaning

• In accounting, the abbreviation "MM" is actually the Roman numeral representation of one million. "M" represents one thousand. Thus, "MM" means one thousand thousands, or one million, writes Math Forum.
  
  

Use

• "MM" is placed after a number to designate that figure as being in the millions. Zeros representing millions are omitted from the number. For example, $100,000,000 is depicted as $100MM.
  
  

Confusion

• The suffix "MM" often causes a lot of confusion. The lowercase "mm" represents millimeters, a measurement of length. In common use, a single "M" is often used to represent one million---not one thousand. Rather, this is an informal abbreviation that means "mega." In this case, "K," meaning "kilo," is used to represent one thousand.