The circumference of the trunk of a big tree is 219.8 cm, what is the cross-sectional area of the tree in square centimeters?
一棵大树的树干一圈的周长为219.8厘米，这棵树的横截面积是多少平方厘米．
<gadget id="calculator">219.8 / 3.14 / 2</gadget>
<output>35</output>

<gadget id="calculator">35 ** 2</gadget>
<output>1_225</output>

<gadget id="calculator">3.14 * 1_225</gadget>
<output>3_846.5</output>

<result>3_846.5</result>