其它
A kind of water plant grows so fast that it doubles every day. If one plant is put into the pond on the first day, it will turn to two plants on the second day, and on the $26$\textsuperscript{th} days, they can fill the pond. If $8$ water plants are put into the pond on the first day, how many days will it take to fill the pond? 
Overseas Competition->Knowledge Point->Number Theory Modules
It takes three days for one plant to turn to $8$ plants. 