Cut a cylinder with a height of 10 decimeters along the height into a number of equal fan-shaped geometric bodies at the bottom, and then assemble it into an approximate cuboid. It is known that the surface area of the assembled cuboid is 40 square decimeters larger than that of the cylinder ． What is the volume of the original cylinder in cubic decimeters?
把一个高为10分米的圆柱体沿高切成底面是若干相等的扇形的几何体，再拼成一个近似的长方体，已知拼成的长方体的表面积比圆柱体的表面积增加了40平方分米．原来圆柱体的体积是多少立方分米．
<gadget id="calculator">40 / 2 / 10</gadget>
<output>2</output>

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

<gadget id="calculator">3.14 * 4 * 10</gadget>
<output>125.6</output>

<result>125.6</result>