Hi Larry,

I have not seen MM as an abbreviation for million but I did find a reference to it in Wikipedia.

M is the Roman numeral for 1,000 but in the metric system M designates the prefix mega- which is a million. For example MW is a megawatt. On the other hand m designates milli- or one thousandth so mm is a millimetre or 0.001 metres.

To minimize confusion I would stick with K for a thousand. K comes form the Greek kilo which means a thousand. In the metric system lower case k designates kilo as in kg for kilogram, a thousand grams. Even here there is some ambiguity. In the language of computer science K is 2¹⁰ = 1024.

Penny