A cylindrical iron sheet ventilation pipe has a bottom radius of 10cm and a length of 3m. To make such a ventilation pipe, how much iron sheet is needed in m**2.
一个圆柱形铁皮通风管，底面半径是10cm，长是3m，做这样的一个通风管，需铁皮多少m**2．
<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">2 * 3.14 * (1/10) * 3</gadget>
<output>1.884</output>

<result>1.884</result>