If a piece of cylindrical wood with a length of 20 decimeters is split along the diameter of the bottom surface, the surface area increases by 80 square decimeters. What is the surface area of the original piece of cylindrical wood?
把一段长20分米的圆柱形木头沿着底面直径劈开，表面积增加80平方分米，原来这段圆柱形木头的表面积是多少．
<gadget id="calculator">80 / 2 / 20</gadget>
<output>2</output>

<gadget id="calculator">2 / 2</gadget>
<output>1</output>

<gadget id="calculator">1 ** 2</gadget>
<output>1</output>

<gadget id="calculator">3.14 * 1</gadget>
<output>3.14</output>

<gadget id="calculator">3.14 * 2</gadget>
<output>6.28</output>

<gadget id="calculator">3.14 * 2 * 20</gadget>
<output>125.6</output>

<gadget id="calculator">6.28 + 125.6</gadget>
<output>131.88</output>

<result>131.88</result>