At the board, during a class presentation, he re-derived the equation for the moment of inertia of a thin rod—this time from scratch, using the method of integration he had traced in the PDF’s example. When a junior asked how he had come to understand the complex steps, he recounted a habit he had developed: "Read the derivation, then re-derive without looking. If you can’t, you haven’t understood it." The junior laughed and asked where to get the PDF. Arjun hesitated, then recommended they check the school library and the publisher’s authorized channels, mindful of quality and ethics.