How much is a thousand million million?

Answer 1

A million is universally 1 x 10^6, and a thousand is 1 x 10^3,
so a thousand million million is 1 x 10^15 or 1,000,000,000,000,000.

In the "short scale" used by the US, this is a thousand trillion or a "quadrillion."

In the "long scale," where a billion is a million million, this is simply one thousand billion.