A piece of square steel is 4 meters long, and its cross section is a square with side length 4 cm. How many kilograms are in this piece of square steel? (1 cubic decimeter of steel weighs 7.8 kg)
一段方钢长4米，横截面是边长为4厘米的正方形，这段方钢中多少千克？(1立方分米钢重7.8千克)
<gadget id="calculator">4 / 10</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">4 * 10</gadget>
<output>40</output>

<gadget id="calculator">(2/5) * (2/5) * 40 * 7.8</gadget>
<output>49.92</output>

<result>49.92</result>