Oooh, it looks like we're giving Erasmus brainteasers, so I have one! This deals with infinite numbers, so I predict that I will pose the question, Erasmus will correctly answer it, and then five people will jump up to tell us both that not only is Erasmus wrong, but the question itself is meaningless gibberish.

Ok, here goes:

An infinitely long tube filled with orange pingpong balls numbered 1,2,3,4,... is pouring balls (in order) at an ever-increasing rate: at first they are going at 1 ball per minute, but after every 10 balls pour, the rate doubles. The balls are being poured into a bucket, over which an evil gremlin is standing chucking out balls, starting with the lowest numbered ball in the bucket. At first he chucks out one ball in 10 minutes, but then waits half as much time after each ball before chucking out the next, so he chucks out ball #1 at the 10 minute mark, ball #2 at the 15 minute mark, ball #3 at 17:30, etc.

Question: how many balls are in the bucket after 10 minutes? After 15 minutes? After 17 and a half minutes? After 19:59? After 20 minutes?

p.s. If you have any other mathematical brainteasers, throw 'em at me!