To make a cylindrical white tin ventilation pipe with a length of 2 meters and a diameter of 0.15 meters, at least how many square meters of white tin is needed.
做一根长2米，管口直径0.15米的圆柱形白铁皮通风管，至少需要白铁皮多少平方米．
<gadget id="calculator">3.14 * 0.15 * 2</gadget>
<output>0.942</output>

<result>0.942</result>