Cut a piece of cylindrical wood with a length of 5 decimeters into two pieces along the diameter, and increase the surface area by 20 square decimeters, find the volume of the original cylindrical wood.
把一段长5分米的圆柱体木料沿着直径往下切成两块，表面积增加20平方分米，求原来圆柱体木料的体积．
<gadget id="calculator">20 / 2 / 5</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 * 5</gadget>
<output>15.7</output>

<result>15.7</result>