Lily Pads
Riddle: In a pond, there is a patch of lily pads. Each day, the lily pads double in size. If it takes the lily pads 48 days to cover the whole pond, how many days does it take to cover half the pond?
Answer: 47 days. Whatever day the lily pads covered half the pond, the whole pond would be covered the next day.
Source: https://www.riddles.com/2638
