The circumference of a semicircle is 20.56 centimeters, what is the area of the whole circle in square decimeters?
一个半圆的周长是20.56厘米，它的整圆面积是多少平方分米？
<gadget id="calculator">2 + 2</gadget>
<output>4</output>

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

<gadget id="calculator">3.14 * 16</gadget>
<output>50.24</output>

<result>50.24</result>