Okay, I have a10-sided die. I'm looking for occurrences of1's and6's when I roll it.

On a single role, the chance that I'll get a 1 or a 6 is20%.

I know that much.

But lets say I don't get it on the first roll. Or the first four?

Here's what I'm trying to figure out:

Probability says that if I roll a d10, there's a 1 in 5 chance that I'll get a 1 or a 6 as a result. If I keep rolling, I'm GOING to get a 1 or a 6 eventually.

What are the odds that it'll happen within the first four tries?

What are the odds that two of the results will be 1 or 6?

Three of the results?

All four?