You have ten boxes of one-pound gold bars, one of which contains counterfeits with bars weighing one-twentieth of a pound less than real bars. With only one weighing, how can you determine the counterfeit box?
Eye Hack: Gray Square Illusion
Our brain is especially adept at interpreting the effects of lighting. We interpret this picture as a cylinder casting a shadow on a chessboard. And so square B should be lighter than square A, only, it’s in the shadow. Actually, the two squares are exactly the same shade.
