If a 4-meter-long log is cut into three small logs, the surface area increases by 16 square decimeters. What is the original volume of the log?
把一根4米长的圆木截成三段小圆木，表面积增加16平方分米，这个圆木的体积原来是多少平方分米
<gadget id="calculator">16 / 4</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>