To make a cylindrical tin bucket without a cover, the diameter of the bottom surface is 4 decimeters, and the height is 5 decimeters. What is the minimum area of the iron sheet?
做一个无盖的圆柱形铁皮水桶，底面直径为4分米，高为5分米，至少需要多大面积的铁皮？
<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</gadget>
<output>12.56</output>

<gadget id="calculator">62.8 + 12.56</gadget>
<output>75.36</output>

<result>75.36</result>