A certain bacterium divides every half hour (from one to two) during the cultivation process. If this bacterium divides from 1 to 16, how many hours will this process take
某种细菌在培养过程中，每半小时分裂一次(由一个分裂成两个)．若这种细菌由1个分裂成16个，这个过程要经过多少小时
<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">0.5 * 4</gadget>
<output>2</output>

<result>2</result>