mm is mille mille, meaning a thousand thousand. 1,000 * 1,000 is 1 million. 1mm to mean 1 million is common outside of the United States.

I live outside the United States and have never seen mm mean anything other than millimeter

Meanwhile I live in the UK and it's completely standard for monetary quantities.

The Financial Times recently changed their abbreviation for million from “m” to “mn” to help screen readers. They would typically read an m suffix as metres; I guess the FT chose mn rather than mm so that screen readers would not say millimetres instead of million.

I’ve seen that use for sure. Perhaps a little telling we’re talking about blockchain tech and that’s what people are using. Is it really about a fast distributed transaction log, or… is it about the money first.

I am American and commonly see mm to mean million.

It has to be capitalized. 1.5MM is 1.5 million. 1.5mm is 1.5 millimeters.

There's a difference between mm and MM.