I think it's interesting that whenever people say the word "billion", they really "billion".  Just listen to the news or any financial thing on TV or radio.  It says, "The company late yesterday reported sales climbed to $1.75 billion..."  Say it out loud.  It just comes out as billion.  You don't say things like, "I paid 18 thousand for my car," or "My electric bill last month was one hundred twenty bucks".  It's more like, "Eh I paid about 18 K," and "A hundred twenty smackers".  But unless you're Byronn Memmelaar (I wonder if he reads my blog), you don't throw around terms like "A couple bil" or "Eh just a few million".