Split a piece of cylindrical wood with a length of 5 decimeters along the diameter of its bottom surface. The measured area of the section is 20 square decimeters. Find the surface area of the original piece of log.
把一段长5分米的圆柱形木头，沿其底面直径劈开，测得剖面面积是20平方分米，求原来这段圆木的表面积．
<gadget id="calculator">20 / 5 / 2</gadget>
<output>2</output>

<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 * 5</gadget>
<output>62.8</output>

<gadget id="calculator">25.12 + 62.8</gadget>
<output>87.92</output>

<result>87.92</result>