If the circumference of a semicircle is 102.8 cm, what is its area in square centimeters?
一个半圆的周长是102.8厘米，它的面积是多少平方厘米．
<gadget id="calculator">102.8 / 5.14</gadget>
<output>20</output>

<gadget id="calculator">20 ** 2</gadget>
<output>400</output>

<gadget id="calculator">400 / 2</gadget>
<output>200</output>

<gadget id="calculator">3.14 * 200</gadget>
<output>628</output>

<result>628</result>