In the UK one billion = 1,000,000,000,000, (10^12) in the US, 1,000,000,000 (10^9). In the US, one trillion = 10^12 in the UK, 10^18. In the US one quadrillion = 10^15, in the UK 10^24.
There seems to be an inconsistency here. In the US, incrementing the prefix part of -llion seems to mean three orders of magnitude, in the UK six. Therefore is, a trillion(US) = 10^3 x billion(US), while a trillion(UK) = 10^6 x billion(UK). And so forth for quadrillion, quintillion, etc. Therefore, 1,000,000 billion(UK) would be either be a trillion(UK) or 1,000,000 billion(US) would be a quadrillion(US).
I need to know, I might want to buy one of those clocks, since I'm often late and if I had a clock with one 10^-15 second resolution I might be OK, I really need one with 10^-24 second resolution.
I shouldn't worry you'll spend the extra time taking your shoes off at the airport anyway.
What we call a billion, they call a milliard. I think!