A cylinder with a height of 5 decimeters is transformed into an approximate cuboid, and the surface area increases by 40 decimeters square. What is the volume of this cylinder in cubic decimeters?
一个高5分米的圆柱，转化成近似长方体，表面积增加了40平方分米，这个圆柱的体积是多少立方分米．
<gadget id="calculator">40 / 2 / 5</gadget>
<output>4</output>

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

<gadget id="calculator">3.14 * 16 * 5</gadget>
<output>251.2</output>

<result>251.2</result>