Cut a cylinder with a base radius of 5dm into a cuboid, the surface area of which is 100dm**2 larger than the original, find the volume of the cylinder.
把一个底面半径是5dm的圆柱切拼成一个长方体，表面积比原来多100dm**2，求圆柱体积．
<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">100 / 2 / 5</gadget>
<output>10</output>

<gadget id="calculator">3.14 * 25 * 10</gadget>
<output>785</output>

<result>785</result>