If a cylindrical piece of wood is cut into 3 sections, the surface area increases by 15.6 square decimeters, what is the area of the bottom of this piece of wood in square decimeters?
把一根圆柱形木料横截成3段，表面积增加了15.6平方分米，这根木料的底面积是多少平方分米．
<gadget id="calculator">15.6 / 4</gadget>
<output>3.9</output>

<result>3.9</result>