Wind a coil with copper wire and wind it 200 times. It is known that the radius of the coil is 1.5 cm. How long is the copper wire at least?
用铜丝绕线圈，绕了200圈，已知这个线圈的半径是1.5厘米，这根铜丝至少长多少米？
<gadget id="calculator">200 / 100</gadget>
<output>2</output>

<gadget id="calculator">2 * 3.14 * 1.5 * 2</gadget>
<output>18.84</output>

<result>18.84</result>