A cylinder with a base radius of 2 decimeters and a height of 4.5 decimeters, find its surface area.
一个圆柱底面半径是2分米，高是4.5分米，求它的表面积．
<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">3.14 * 4 * 2</gadget>
<output>25.12</output>

<gadget id="calculator">3.14 * 2 * 2 * 4.5</gadget>
<output>56.52</output>

<gadget id="calculator">25.12 + 56.52</gadget>
<output>81.64</output>

<result>81.64</result>