One thousand thousands is a million - 1,000,000.
Therefore a Billion, is One thousand, one thousand thousands - 1,000,000,000 - or as you asked, one thousand million.
I have a feeling this is American format - I think in English terms a billion used to be a million million - but it's all changed now!
Aimee is correct, a billion is 1,000,000,000 or a thousand million and yes, the British billion used tobe a thousand times greater but mercifully it was standardised (to the Yank version of course!)
Are you sure an American billion is a hundred thousand million, not a thousand million. It's very confusing amount, however much it is. And how much is a trillion now? And a quadrillion? And a quintillion?