To make a cuboid chimney with a length of 6m, a width of 1m, and a height of 0.5m, how much iron sheet is needed at least?
制作一个长6m、宽1m、高0.5m的长方体的烟筒，至少需要多少铁皮？
<gadget id="calculator">6 * 1 * 2</gadget>
<output>12</output>

<gadget id="calculator">6 * 0.5 * 2</gadget>
<output>6</output>

<gadget id="calculator">12 + 6</gadget>
<output>18</output>

<result>18</result>