A piece of square steel has a cross-section of a square with a side length of 5 cm and a length of 120 cm. The weight of steel per cubic decimeter is 7.8 kg. How much does this square steel weigh?
一根方钢，横截面是边长5cm的正方形，长120cm，每立方分米钢重7.8千克，这根方钢重多少千克？
<gadget id="calculator">5 / 10</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">120 / 10</gadget>
<output>12</output>

<gadget id="calculator">(1/2) * (1/2) * 12</gadget>
<output>3</output>

<gadget id="calculator">3 * 7.8</gadget>
<output>23.4</output>

<result>23.4</result>