A cylindrical bucket (without a lid) has a base radius of 2 decimeters and a height of 5 decimeters. What is the minimum square decimeter of wood used to make this bucket?
一个圆柱形的水桶(无盖)，底面半径2分米，高5分米．做这个水桶至少要用木板多少平方分米？
<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>