There is a piece of steel with a length of 2.5 meters and a cross-sectional area of 40 square centimeters. If this steel weighs 7.8 kilograms per cubic decimeter, how many kilograms does this steel weigh?
有一根长2.5米、横截面积是40平方厘米的钢材．如果这种钢材每立方分米重7.8千克，这根钢材重多少千克？
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">2.5 * 10</gadget>
<output>25</output>

<gadget id="calculator">(2/5) * 25 * 7.8</gadget>
<output>78</output>

<result>78</result>