section of square steel, 2.5m long, has a cross-section of a square with side length 6cm. How much does this piece of square steel weigh? (7.8kg in 1dm**3 steel)
一段方钢，长2.5m，横截面是边长为6cm的正方形．这段方钢有多重？(1dm**3钢中7.8kg)
<gadget id="calculator">6 / 10</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">2.5 * 10 * (3/5) * (3/5) * 7.8</gadget>
<output>70.2</output>

<result>70.2</result>