Cutting a cylinder into an approximate cuboid increases the surface area by 200 square centimeters. The height of the cylinder is 20 cm, what is the volume of the cylinder in cubic centimeters?
把一个圆柱切拼成一个近似的长方体，表面积比原来增加200平方厘米．圆柱的高是20厘米，圆柱的体积是多少立方厘米．
<gadget id="calculator">20 ** 2</gadget>
<output>400</output>

<gadget id="calculator">3.14 * 400 * 20</gadget>
<output>25_120</output>

<result>25_120</result>