To make two cylindrical chimneys, each of which is 1 meter long and has a bottom diameter of 20 cm, how many square meters of iron sheet is needed?
做2节圆柱形烟囱，每节长1米，底面直径是20厘米的铁皮烟囱，至少需要多少平方米的铁皮？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">3.14 * (1/5) * 1 * 2</gadget>
<output>1.256</output>

<result>1.256</result>