A cylindrical tin bucket without a cover, the bottom diameter and height are both 4dm, how many square decimeters of tin should be used to make such a bucket?
一个没有盖的圆柱形铁皮水桶，底面直径和高都是4dm，做一只这样的水桶至少要用多少平方分米铁皮？
<gadget id="calculator">3.14 * 4 * 4</gadget>
<output>50.24</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">50.24 + 12.56</gadget>
<output>62.8</output>

<result>62.8</result>