How many square decimeters of iron sheet is needed to make a cylindrical oil drum with a height of 5 decimeters and a bottom diameter of 4 decimeters? (Retain integers)
要用铁皮制造一个高5分米，底面直径是4分米的圆柱形油桶，需要铁皮多少平方分米？(得数保留整数)
<gadget id="calculator">3.14 * 4 * 5</gadget>
<output>62.8</output>

<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">3.14 * 4 * 2</gadget>
<output>25.12</output>

<gadget id="calculator">62.8 + 25.12</gadget>
<output>87.92</output>

<result>87.92</result>