When a 2-meter-long square log is sawn into two equal pieces, the surface area increases by 4 square decimeters. What is the volume of this square log in cubic decimeters?
把一根长2米的方木锯成相同的两段后，表面积增加了4平方分米．求原来这根方木的体积是多少立方分米？
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

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

<gadget id="calculator">2 * 20</gadget>
<output>40</output>

<result>40</result>