Dr. Johnson bought a new plant for his aquarium that was growing very fast. Every day it was doubling in size. On the 30th day the plant covered the whole aquarium. On which day did it cover half of the aquarium?
Dr. Johnson bought a new plant for his aquarium that was growing very fast. Every day it was doubling in size. On the 30th day the plant covered the whole aquarium. On which day did it cover half of the aquarium?