Are some randoms more random than others?

[tinkthank]

Heh thanks.
I always wondered: If there is a 1% chance of an event happening, and you looked at 100 possible event-worlds, what are the chances of it happening once? If it is 1/100 + 1/100 ..., wouldnt that make it 100/100? Does that mean there is a 100% chance of it happening? That just sounds absurd to me. Obviously, "chances are" that it will happen, but what the heck does that mean? (Is my question clear or must I be more precise?)