A 4-meter-long square log is sawed into two pieces, and the surface area is increased by 8 square decimeters. What is the original volume of this square log in cubic decimeters?
把一根4米长的方木锯成两段，表面积增加了8平方分米，原来这根方木的体积是多少立方分米
<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">4 * 10</gadget>
<output>40</output>

<gadget id="calculator">4 * 40</gadget>
<output>160</output>

<result>160</result>