A log, the circumference of its cross section is 62.8 cm, find their cross-sectional area.
一根圆木，它的横截面的周长是62.8厘米，求它们的横截面积．
<gadget id="calculator">62.8 / 3.14 / 2</gadget>
<output>10</output>

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

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

<result>314</result>