A cylindrical steel bar is 8 decimeters long. If the steel bar is cut into 5 equal sections, the surface area will increase by 25.12 square decimeters. What is the volume of this cylinder in cubic decimeters?
一根柱形钢条长8分米，如果把这个钢条截成相等的5段，表面积会增加25.12平方分米，这个圆柱的体积是多少立方分米．
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

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

<gadget id="calculator">25.12 / 8</gadget>
<output>3.14</output>

<gadget id="calculator">3.14 * 8</gadget>
<output>25.12</output>

<result>25.12</result>