Divide the bottom surface of a cylinder with a height of 5 cm into several equal parts, cut the cylinder and assemble it into an approximate cuboid. The surface area of the cuboid is 20 square centimeters larger than that of the cylinder. Find the volume of the original cylinder.
把高5厘米的圆柱底面分成若干等份，把圆柱切开拼成一个近似的长方体，长方体表面积比圆柱增加20平方厘米．求原来圆柱的体积．
<gadget id="calculator">20 / 2 / 5</gadget>
<output>2</output>

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

<gadget id="calculator">3.14 * 4 * 5</gadget>
<output>62.8</output>

<result>62.8</result>