To make a cylindrical ventilation pipe with a length of 1.5 meters and a cross-sectional diameter of 2 decimeters, at least how many square meters of iron sheet is required.
做一个长1.5米，横截面直径是2分米的圆柱形通风管，至少需要多少平方米的铁皮．
<gadget id="calculator">2 / 10</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">3.14 * (1/5) * 1.5</gadget>
<output>0.942</output>

<result>0.942</result>