After cutting a 20 decimeter long cylindrical log into 5 sections, the surface area increases by 80 square decimeters, what is the volume of this piece of log?
把一段长20分米的圆柱形木头截成5段后，表面积增加了80平方分米，那么这段圆木的体积是多少？
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">2 * 4</gadget>
<output>8</output>

<gadget id="calculator">80 / 8</gadget>
<output>10</output>

<gadget id="calculator">10 * 20</gadget>
<output>200</output>

<result>200</result>