Fill in the numbers according to the law: 18, 9, 4.5, 2.25, 1.125, how much, 0.28125.
按规律填数：18，9，4.5，2.25，1.125，多少，0.28125．
<gadget id="calculator">2.25 / 2 / 2</gadget>
<output>0.5625</output>

<result>0.5625</result>