A thin steel wire with a length of 628 mm is wound exactly 10 times on a round iron rod. What is the cross-section of the round iron rod in square millimeters?
628毫米长的细钢丝在一根圆铁棒上刚好绕10圈，这样圆铁棒的横截面是多少平方毫米．
<gadget id="calculator">628 / 10 / 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>