To make a 12-section cuboid iron chimney, each section is 2 decimeters long, 4 decimeters wide, and 0.5 meters high, how many square meters of iron sheets should be used at least?
要制作12节长方体的铁皮烟囱，每节长2分米，宽4分米，高0.5米，至少要用多少平方米的铁皮？
<gadget id="calculator">2 / 10</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/5) * 0.5</gadget>
<output>0.1</output>

<gadget id="calculator">4 / 10</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(2/5) * 0.5</gadget>
<output>0.2</output>

<gadget id="calculator">0.1 + 0.2</gadget>
<output>0.3</output>

<gadget id="calculator">0.3 * 2 * 12</gadget>
<output>7.2</output>

<result>7.2</result>