Seriously, there are 24 hours in a day and 365 days in a year…this is 2007, so around 17,581,320. Is that better?

The Earth formed around 4.57 billion years ago. At present, the Earth orbits the Sun once for every roughly 366.26 times it rotates about its axis. This length of time is a sidereal year, which is equal to 365.26 solar days.

366.26 days * 24 hours per day (presuming the Earth has rotated and revolved consistently for 4.57 billion years, which it has not) = 8790.24 hours per year. 8766.24 hours * 4.57 billion = 40 trillion hours (40,171,396,800,000).

But I’m not a mathematician or a physicist.

I like Nunya’s answer above. The only measure of an hour is the Earth’s rotation. Therefore, the Earth has been here for all the hours. Since the Universe was here before the Earth (even by creationist myth), the Universe has been here for all of them, too.