A copper wire is wound exactly 10 times on a circular tube with a diameter of 20 cm. What is the approximate length of the copper wire in cm?
一根铜丝在直径20cm的圆管上正好绕了10圈，这根铜丝约长多少cm．
<gadget id="calculator">3.14 * 20 * 10</gadget>
<output>628</output>

<result>628</result>