To make a cylindrical chimney with a length of 1m and a diameter of 12cm, at least how many cm**2 iron sheets are needed.
做一节长1m，直径为12cm的圆柱形烟囱，至少要多少cm**2的铁皮．
<gadget id="calculator">3.14 * 12 * 1 * 100</gadget>
<output>3_768</output>

<result>3_768</result>