I get confused because almost always i see drop rates in the form 1/x (where x is a natural number :P).

 

But it's most accurate to think of them as arbitrarily long decimals that get rounded, i think. But my question is to what place are they rounded??

RS uses a random number generator for everything. I can't be certain what the number is, but assuming a roll has 1024 possible outcomes. A drop would be whenever a roll is a certain number, so there can't be any decimals beyond 1/1024. a common drop may have 256 occurances out of 1024, while a rare drop may have 1 or 2 occurances.

 

1024 is just a guess, it's probably more precise than that.

That makes so much sense. I remember now. Thanks! I guess effigies/charms, etc., are introduced the same way.

Why do you suspect this, Enfield?

Thread locked, the OP's question has been answered. :)