10,000 million is 10 000 000 000. In scientific notation, this is 1 x 1010.
In Canada, USA and many countries, a "billion" is 109, so we'd say this is 10 billion.
In the UK, however, the word "billion" has undergone a change. Traditionally, it was defined as 1012, and the word "milliard" represented 109. Some countries still use this older form, but the UK and many other countries now use "billion" to mean 109 as well. Still, it is easy to confuse someone who doesn't know which form you
That's why in the UK, people say 10,000 million. So when you are dealing with an international audience, you should try to avoid using the word "billion".
Stephen La Rocque.>
PS: Other large numbers like "trillion" and "quadrillion" are in the same situation. You can see a long list of these confusing names for large numbers at Billions and more! and a few more at Billions and more! and even more! That's why scientific notation is a good choice when expressing large numbers: there is no ambiguity in it.