I'm based in Europe and a native English speaker, I thought I was aware of most of the differences between UK/US English. I can't believe I have worked with Americans for decades and never noticed this. Live and learn!

I'm an American, and both methods sound right to my ears. I hear both variations quite a lot from the people around me. I assume it depends on what part of the US you're from.

American English traditionally uses an “and” to separate the whole from the fraction, e.g. two thousand eight and two thirds.