Hello Math-Fun, ... slightly adapted from a puzzle found here (might be old hat): "This Book Does Not Exist: Adventures In The Paradoxical", by Gary Hayden and Michael Picard; +---+---+---+---+---+ | 0 | 0 | 0 | 0 | 0 | +---+---+---+---+---+ | 0 | 1 | 2 | 3 | 0 | +---+---+---+---+---+ | 0 | 4 | 5 | 6 | 0 | +---+---+---+---+---+ | 0 | 7 | 8 | 9 | 0 | +---+---+---+---+---+ | 0 | 0 | 0 | 0 | 0 | +---+---+---+---+---+ You wake up tighten on a chair in one of the cubic cells with number 1 to 9 -- but in which one? You are surrounded by four similar walls -- you don't know which one you are facing: for instance, should you be in cell #4, wouldn't you know if you are facing the wall between your cell and the cell #7, or #5, or #1 or #0. You may ask two questions to the warden -- one after the other; he will give you the correct answers, one after the other. The questions you may ask are only those: - What cell number has the cell in front of me? - What cell number has the cell on my right? - What cell number has the cell behind me? - What cell number has the cell on my left? If you then guess the cell number you are occupying, you will be free -- if not you'll be killed. What are my survival odds if I'm a good math-puzzler? Best, É.