If a cylinder with a height of 1 meter is sawn into two pieces, the surface area is increased by 4 square decimeters, what is the original volume of the cylinder in cubic decimeters?
把高1米的圆柱体锯成两段，表面积增加4平方分米，原来圆柱的体积是多少立方分米．
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">2 * 1 * 10</gadget>
<output>20</output>

<result>20</result>