The lotus in the pond reproduces very fast, doubling every day. By the 15th day, half of the pond has grown, so how many days can the whole pond be covered?
池塘里的莲花繁殖得特别快，每天增多1倍．到第15天的时候长了半个池塘，那么第几天能长满整个池塘呢？
<result>16</result>