To make a cuboid iron chimney with 15 sections, each section is 4 decimeters long, 3 decimeters wide, and 2 meters high, how many square meters of iron sheets should be used at least?
要制作15节长方体的铁皮烟囱，每节长4分米，宽3分米，高2米，至少要用多少平方米的铁皮？
<gadget id="calculator">2 * 10 * 4</gadget>
<output>80</output>

<gadget id="calculator">2 * 10 * 3</gadget>
<output>60</output>

<gadget id="calculator">80 + 60</gadget>
<output>140</output>

<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">140 * 2 * (3/20)</gadget>
<output>42</output>

<result>42</result>