A thin iron wire of 65 cm is wound 10 times on a round iron rod and there is still 2.2 cm left. What is the cross-sectional area of this round iron rod in square centimeters?
有一条65厘米的细铁丝在一根圆铁棒上绕10圈后还剩2.2厘米，这根圆铁棒的横截面的面积是多少平方厘米？
<gadget id="calculator">65 - 2.2</gadget>
<output>62.8</output>

<gadget id="calculator">62.8 / 10 / 2 / 3.14</gadget>
<output>1</output>

<gadget id="calculator">3.14 * 1 * 1</gadget>
<output>3.14</output>

<result>3.14</result>