Respuesta :
Do you mean squared? 81 ft and then a 2 at the top. If so it means 81 feet squared and it indicates 81 times 81 which would be 6561 feet.
81 feet 2, means 81 feet, 2 inches as the length of something, as when somebody is "6 foot 2," they are 6 feet, 2 inches tall.