If you want to make a cylindrical chimney with 10 sections, 3m in length and 9.42dm in circumference, how much iron sheet is needed at least?
想做10节长3m，底面周长是9.42dm的圆柱形烟囱，至少需要多少铁皮？
<gadget id="calculator">3 * 10</gadget>
<output>30</output>

<gadget id="calculator">9.42 * 30 * 10</gadget>
<output>2_826</output>

<result>2_826</result>