A cuboid iron chimney, the bottom surface is a square with a side length of 3 decimeters and a height of 4 meters. How many square meters of iron sheet should be used to make such a chimney?
一种长方体铁皮烟囱，底面是边长3分米的正方形，高4米，制这样一节烟囱至少要用铁皮多少平方米？
<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">4 * (3/10) * 4</gadget>
<output>24/5 = around 4.8</output>

<result>24/5 = around 4.8</result>