A piece of round white paper with a diameter of 20 cm. Divide this piece of white paper into 5 parts on average, and use up one of the parts. The used part is ((())/(()) of this white paper. ), is how many square centimeters.
一张圆形白纸，直径是20厘米，把这张白纸平均分成5份，用去了其中的1份，用去部分的是这张白纸的((())/(()))，是多少平方厘米．
<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">3.14 * 100</gadget>
<output>314</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">314 * (1/5)</gadget>
<output>314/5 = around 62.8</output>

<result>314/5 = around 62.8</result>