It is planned to make a cylindrical bucket without a cover, the radius of the bottom is 2 decimeters, and the height is 5 decimeters. How many square decimeters of iron sheet is needed to make this bucket.
计划制作一个没盖的圆柱形水桶，底面半径是2分米，高是5分米，制作这个水桶至少需要铁皮多少平方分米．
<gadget id="calculator">3.14 * 2 * 2 * 5</gadget>
<output>62.8</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>