A cylindrical tin bucket without a lid has a bottom diameter and a height of 4 decimeters. What is its surface area in square centimetres.
一个无盖圆柱形铁皮水桶，底面直径和高都是4分米．它的表面积是多少平方分米．
<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">3.14 * 4 * 4</gadget>
<output>50.24</output>

<gadget id="calculator">12.56 + 50.24</gadget>
<output>62.8</output>

<result>62.8</result>