Cut a cone of wood with a base circumference of 25.12 decimeters along the height, and the surface area increases by 40 square decimeters. What is the original volume of the cone in cubic decimeters?
把一个底面周长为25.12分米的圆锥木料沿高切开，表面积增加了40平方分米，这个圆锥原来的体积是多少立方分米．
<gadget id="calculator">25.12 / 3.14</gadget>
<output>8</output>

<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<gadget id="calculator">40 / 2</gadget>
<output>20</output>

<gadget id="calculator">2 / 8</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">20 * (1/4)</gadget>
<output>5</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">3.14 * 16 * 5 * (1/3)</gadget>
<output>83.733333</output>

<result>83.733333</result>