Ironically, this reminds me of a story (folk tale?) about Von Neumann himself. A colleague told him about the Two Trains Problem (https://mathworld.wolfram.com

Ironically, this reminds me of a story (folk tale?) about Von Neumann himself. A colleague told him about the Two Trains Problem (https://mathworld.wolfram.com/TwoTrainsPuzzle.html https://mathworld.wolfram.com/TwoTrainsPuzzle.html), and Von Neumann replied with the correct answer. When his colleague said, "Ah! You figured out he trick!", Von Neumann replied, "What trick? I just summed up the distances in my head!"