What is the area of a semicircle surrounded by 20.56 cm long iron wire?
用20.56厘米长的铁丝围成一个半圆形，它的面积是多少平方厘米．
<gadget id="calculator">2 + 2</gadget>
<output>4</output>

<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<gadget id="calculator">16 / 2</gadget>
<output>8</output>

<gadget id="calculator">3.14 * 8</gadget>
<output>25.12</output>

<gadget id="calculator">25.12 / 2</gadget>
<output>12.56</output>

<result>12.56</result>