After folding a rope in half four times, the length is 25 meters. How long is this rope in meters?
把一根绳对折4次后，长度是25米．这根绳全长是多少米？
<gadget id="calculator">2 ** 4</gadget>
<output>16</output>

<gadget id="calculator">1 / 16</gadget>
<output>1/16 = around 0.0625</output>

<gadget id="calculator">25 / (1/16)</gadget>
<output>400</output>

<result>400</result>