A piece of wood is 1 meter long and has a square cross-section. If it is cut into 4 sections, the surface area increases by 15 square decimeters. What is the volume of this piece of wood?
有一根木料长1米，截面是正方形，如果把它截成4段，表面积增加了15平方分米，这根木料的体积是多少？
<gadget id="calculator">15 / 6</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">(5/2) * 1 * 10</gadget>
<output>25</output>

<result>25</result>