Two identical cylinders can be put together to form a cylinder with a height of 4 decimeters, but the surface area is reduced by 50.24 decimeters square. What is the volume of a cylinder.
两个完全一样的圆柱能拼成一个高4分米的圆柱，但表面积减少了50.24平方分米．原来一个圆柱的体积是多少．
<gadget id="calculator">50.24 / 2</gadget>
<output>25.12</output>

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

<gadget id="calculator">25.12 * 2</gadget>
<output>50.24</output>

<result>50.24</result>