A piece of square steel is 4 meters long and its cross-section is a square with an area of 2.5 square decimeters. What is the volume of this piece of square steel?
一段方钢长4米，横截面是面积2.5平方分米的正方形，这段方钢的体积是多少立方分米．
<gadget id="calculator">4 * 10</gadget>
<output>40</output>

<gadget id="calculator">2.5 * 40</gadget>
<output>100</output>

<result>100</result>