Master Li used iron sheets to make a square with a side length of 5 decimeters and a cuboid chimney with a height of 4 meters. How many square meters of iron sheets were used?
李师傅用铁皮做一个底面是边长5分米的正方形，高是4米的长方体烟囱，一共用了多少平方米的铁皮？
<gadget id="calculator">5 / 10</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">4 * (1/2) * 4</gadget>
<output>8</output>

<result>8</result>