A garden pond shaped like an ellipse — longer diameter L, shorter diameter S. How much area does it cover? In 850 CE, Mahāvīra's answer: take S/4, multiply by 2L+S. The formula is approximate — it uses the Indian rounding of π as 3 — but recovers the modern π·a·b correctly for circular limits and stays within ~10% for moderate eccentricities. Indian mensuration teachers kept teaching it for the next thousand years. The first explicit ellipse-area formula in surviving Sanskrit mathematics.