A troop of monkeys is playing. One-eighth of them, squared, skip through a grove; the remaining twelve chatter on a hill. How many monkeys? Bhāskara II's algebra (1150 CE) works the quadratic and reports BOTH answers — 48 and 16 — because both fit. Quadratics have two roots, his textbook teaches, and then goes further: when a root fails the story (a negative troop, a fractional pearl), it must be rejected as incongruous. Solution-validity analysis, five centuries before Europe stopped calling negative roots "false."