Ask HN: What question would AI answer to demonstrate it thinks?

There is a raging debate about LLMs and AIs in general that do not distinguish between probabilistic word selection and thought. Everyone has a different standard. My favorite (which favors not thinking) is "What are the last 10 digits of Pi?" which will give you 10 digits (typically). Another is "Describe all security vulnerabilities in the following code." I'm curious though, what are your questions? The one you would ask that, when answered accurately, would make you pause and think that maybe there was something more here than guessing the next word.