"Illegally selling private salt is punishable by death!" A modern product manager who has transmigrated into the past calmly fights for his survival! While everyone else is busy scheming against one another, he brings out mathematics, physics, and chemistry to crush them with knowledge from a higher dimension. Double-entry bookkeeping brings a century-old noble family to ruin, a spoonful of refined salt lets him monopolize the salt trade across the land, and fluid mechanics allows him to channel water up mountains, earning the people's reverence! From an abandoned pawn to an emperor's revered teacher, in this lifetime, he will use modern science to calculate his way through the entire Great Yan Dynasty!