A piece of square steel is 5 meters long and its cross-section is a square with an area of 9 square decimeters. What is the volume of this square bar in cubic decimeters?
一根方钢，长5米，横截面是一个面积9平方分米的正方形．这块方钢的体积是多少立方分米？
<gadget id="calculator">5 * 10</gadget>
<output>50</output>

<gadget id="calculator">50 * 9</gadget>
<output>450</output>

<result>450</result>