There is a kind of water plant that doubles every day compared with the previous day, and it takes 26 days to cover the pond. How many days does it take to cover half of the pond?
有种水草每天比前一天增一倍，26天长满池塘，长满池塘一半需要多少天．
<gadget id="calculator">26 - 1</gadget>
<output>25</output>

<result>25</result>