"...say half a trillion tonnes of rock falling into the water all at once... "; is that like a one with nine zeroes after it or is it a million times a billion? In the US a billion is a one with nine zeroes after it(a thousand million). In the UK a billion is a million million. In the US a trillion would be a onnnne with 12 zeroes behind it or a million million or one UK billion. Does that mean that a UK trillion would be a million times a million times a million or a one with eighteen zeroes behind it or would it be that a UK billion is the same as a UK trillion when expressed in US terminology?
onnnne = one