Master Huang needs to make a 20-section ventilation pipe with a bottom diameter of 12 decimeters and a length of 3 meters. How much iron sheet is needed?
黄师傅要做20节底面直径是12分米，长是3米的通风管，需要用多少铁皮？
<gadget id="calculator">12 / 10</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">3.14 * (6/5) * 3 * 20</gadget>
<output>226.08</output>

<result>226.08</result>