Roman Numerals, many use that shorthand why do people use mm for million Guilty as charged. Why do I do it? I'm not sure, some habit I formed long long ago... Is it confusing or bothersome? Or just curious? Fwiw I don't see folks use a single-M for thousand, that would be confusing so we go w/ K. Feel free to send me a C-note as a tip. Or maybe a few large, if you're so inclined. But not in PlusOne!