Without correcting for exactly when leap years fell, or for the change between Julian and Grgorian calendars, I make the dates January 1975 (1^9 seconds), May 105AD (1^9 minutes), February 112073BC (1^9 hours), about 2.7 million years ago (1^9 days).

One billion inches woould take you round the world at 50 degrees latitude.

A billion is a little under the estimated volume of the world's oceans in cubic kilometres. And if that seems a lot, don't forget that if the world were the size of a soccer ball, all the depth of the ocean would be a few thousands of an inch, it would just seem to have damp patches on the ever-so-smooth surface. Even Everest would be only a thousandth of an inch high.

I must get a life too. Or a file.