Simulating Many Random Events

I need to accurately (so that it’s not obvious that it’s fake) simulate varying amounts (up to 10^100) of random events with varying chances for a project I’m working on. For small numbers of events, you can just simulate the events individually, but for large values, it’s much more tricky because it would take too long to do each one individually. If the odds are high enough, you can simply multiply the amount of events by the chance to get a good approximation, but I don’t know what to do if there’s a large amount of events and a small chance per event. How can I simulate it? (Doing the trick for a high chance and many events isn’t accurate enough.)

Hmm, I remember getting in trouble in high school physics lab for turning in a faked log of experiments I didn’t want to bother doing based on the very probabilities we were supposed to be discovering… not with a computer, though; I’m older than that. If you want it not to be obviously fake, you want slightly inaccurate probabilities!

I don’t understand why a low probability should work any differently from a high probability, though.

For a high probability, there would be enough of each event outcome that the amounts of each wouldn’t change much anyways. For low ones, you could get an outcome that doesn’t happen at all or happens 10 times from the same chance of an outcome. Basically, the effects of random chance get magnified as you have an outcome happen less.