A cylindrical tin chimney has a bottom diameter of 30 cm and a height of 2 meters. How many square centimeters of tin should be used to make this chimney?
一个圆柱形状的铁皮烟囱，底面直径是30厘米，高是2米，做这个烟囱，至少要用铁皮多少平方厘米？
<gadget id="calculator">2 * 100</gadget>
<output>200</output>

<gadget id="calculator">3.14 * 30 * 200</gadget>
<output>18_840</output>

<result>18_840</result>