From: utzoo!decvax!harpo!npoiv!alice!danny
Newsgroups: net.nlang
Title: Re: billion
Article-I.D.: alice.1533
Posted: Thu Feb 24 09:28:02 1983
Received: Fri Feb 25 03:37:47 1983
References: houti.215

US: billion = 1000 million
    trillion = 1000 billion
    etc

many other countries:
    billion = 1,000,000 million
    trillion = 1,000,000 billion
    etc

For ex., you'll hear the British refer to the population of the
  world as four thousand million while Americans say four billion