Put some duckweed in a pond, the growth rate of duckweed is very fast, and the sleeping area of the water surface covered by duckweed always doubles the area of the water surface covered by the previous day. On the 24th day after stocking, the water surface of the pond was just completely covered. When the water surface covers 25%, it is the first day after stocking.
在一个池塘里放养一些浮萍，浮萍的生长速度很快，每天浮萍覆盖的水面睡眠面积总比前一天覆盖水面面积增加1倍．放养后的第24天，池塘的水面刚好完全被覆盖．水面覆盖25%时是放养后的第多少天．
<gadget id="calculator">24 - 2</gadget>
<output>22</output>

<result>22</result>