Cut a 4-meter-long log into three small logs. If the surface area is increased by 8 square decimeters, what is the original volume of the log in cubic decimeters?
把一根4米长的圆木截成三段小圆木．表面积增加8平方分米，这根圆木原来的体积是多少立方分米．
<gadget id="calculator">8 / 4</gadget>
<output>2</output>

<gadget id="calculator">2 * 4 * 10</gadget>
<output>80</output>

<result>80</result>