To make a 12-section cuboid tin chimney, each section is 2.5 meters long, 4 decimeters wide, and 3 decimeters high, at least how many square meters of iron sheets should be used?
要制作12节长方体的铁皮烟囱，每节长2.5米，宽4分米，高3分米，至少要用多少平方米的铁皮？
<gadget id="calculator">2.5 * 10 * 4</gadget>
<output>100</output>

<gadget id="calculator">2.5 * 10 * 3</gadget>
<output>75</output>

<gadget id="calculator">100 + 75</gadget>
<output>175</output>

<gadget id="calculator">12 / 100</gadget>
<output>3/25 = around 0.12</output>

<gadget id="calculator">175 * 2 * (3/25)</gadget>
<output>42</output>

<result>42</result>