Riddles, brain puzzles and mathematical problems

[BAndrew]

Spoiler below!

I just noticed that my method contains some errors so ignore it. If you think about it though, the absolute minimum amount of rats he needs for him to be sure that he discovers the poison is all of them. The worst case scenario is always going to be that the last bottle he checks is the one that contains the poison, right?

It seems that way, but I promise there is an ingenious way where he can do it with MUCH less rats that you think. Try to think outside the box. I suggest you deal first with smaller numbers (eg 10 bottles)