At a garden shop they’re selling Magic Grass, a patch of sod that doubles in size every day. A man goes to buy some and figures that his garden is big enough that if he buys one patch, it will cover his garden in 14 days, because each day it doubles in size. So he decides to speed up the process, and buys two patches of sods.
How many days will it now take for the Magic Grass to cover his garden?
It will take 13 days to cover his garden with two patches of sods.
With 2 patches of sods, each patch of sod will need to cover half his garden and one patch of sod can cover half his garden in 13 days.