A piece of cylindrical wood with a length of 40 cm is sawn along the diameter of its base. The sum of the surface areas of the two parts obtained is 800 cm2 larger than the original one. What is the volume of the original wood?
一段40厘米长的圆柱形木头沿着其底面直径锯开，所得两部分的表面积之和比原来增加800平方厘米，求原来木头的体积是多少？
<gadget id="calculator">800 / 2 / 40</gadget>
<output>10</output>

<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">3.14 * 25</gadget>
<output>78.5</output>

<gadget id="calculator">78.5 * 40</gadget>
<output>3_140</output>

<result>3_140</result>