To make a cylindrical white iron ventilation pipe with a length of 3 meters and a diameter of the nozzle of 0.2 meters, at least how many square meters of white iron is needed.
做一根长3米，管口直径0.2米的圆柱形白铁皮通风管，至少需要白皮多少平方米．
<gadget id="calculator">3.14 * 0.2 * 3</gadget>
<output>1.884</output>

<result>1.884</result>