A rectangular parallelepiped steel with a length of 2.5m has a cross-section of a square with a circumference of 40cm. If the steel weighs 7.8g per cubic centimeter, how many kilograms does this piece of square steel weigh?
一根长2.5m的长方体方钢，横截面是周长40cm的正方形，如果每立方厘米钢重7.8g，这段方钢有多少千克？
<gadget id="calculator">40 / 4</gadget>
<output>10</output>

<gadget id="calculator">7.8 / 1_000</gadget>
<output>0.0078</output>

<gadget id="calculator">10 * 10 * 2.5 * 100 * 0.0078</gadget>
<output>195</output>

<result>195</result>