The bottom surface of a cuboid fuel tank is a square with a perimeter of 20 decimeters and a height of 8 decimeters. How many square decimeters of iron sheet should be used to make this fuel tank?
一个长方体油箱的底面是周长为20分米的正方形，高是8分米，制作这个油箱至少要用铁皮多少平方分米？
<gadget id="calculator">20 / 4</gadget>
<output>5</output>

<gadget id="calculator">5 * 5 * 2</gadget>
<output>50</output>

<gadget id="calculator">5 * 8 * 4</gadget>
<output>160</output>

<gadget id="calculator">50 + 160</gadget>
<output>210</output>

<result>210</result>