Don't be ridiculous, _obviously_ you roll a d20, subtract one, and the count how many digits the result has

It's called a chance cube and it's essential on tatooine

The old UK £1 was similar in size but twice as thick. It's now 12-sided but not sure how that impacts the odds.

Oh, I still bought the full set, but I tried to get isohedral dice whenever possible.

It has only 1 corner, and 2 surfaces, making it 2 sided. The 2 sides just happen to be curved

I know there's a way to figure that out, but I have no idea where to start. So I'm going with 1 in 3000, plus or minus 42.

4 sided.

Roll a d100, if it is odd 1, 2 if even

Fair point. A ball has either one or infinite sides from my perspective.

Inside, outside, and, depending on the ball, offsides.

I've seen this shape uses as a D4. Nothing cursed about it. About as threatening to me as a Labrador puppy.

this is four sides??

I like how you'd be rolling two d10's, and then completely ignoring one of them.

It has two sides. They're curved, and it doesn't stay on the curve part, so you can effectively use it as a d4, but it's still only two-sided. Sort of like how you can flip a Mobius strip like a coin and it will land one of two ways, but it still only has one side.

It keeps the statisticians happy

That extremely rare, almost-never chance of landing on the edge is exactly what I would program into a game if I made one, instead of exactly 50% odds.

Rare coin flip: Success for every roll over the next hour of gameplay.

Ah, dice lawyering.

Well, but it also has to stay on its edge, and that's a lot less likely...

Looks 4-sided to me