That would be 3,000,000,000 (if you remember a million is represented by six zeros, it's quite easy).
How Do You Write Three Thousand Million In Numeral Form?
I'm not sure, but I don't think you can have 3,000 millions! I guess you would write it like so, 3,000,000,000, but that's an awful lot in fact if you had 3,000 million you would be in the trillions, not millions!