A cylindrical iron sheet ventilation pipe has a cross-sectional diameter of 10 cm and a length of 1 meter. How many square centimeters of iron sheets are needed to make such a ventilation pipe?
一种圆柱形铁皮通风管，横截面的直径是10厘米，长1米，做这样的通风管需要多少平方厘米的铁皮？
<gadget id="calculator">3.14 * 10 * 1 * 100</gadget>
<output>3_140</output>

<result>3_140</result>