A log with a length of 20cm is sawn into three sections, each section is still a cylinder, and the surface area is increased by 0.25cm**2, what is the original volume of the log?
把一根长20cm的圆木锯成三段，每段仍是圆柱，表面积比原来增加了0.25cm**2，这根圆木原来的体积是多少．
<gadget id="calculator">3 - 1</gadget>
<output>2</output>

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

<gadget id="calculator">0.25 / 4</gadget>
<output>0.0625</output>

<gadget id="calculator">0.0625 * 20</gadget>
<output>1.25</output>

<result>1.25</result>