Cut 3 meters from a cylindrical steel with a cross-sectional diameter of 5 decimeters, and the steel weighs 7.8 kilograms per cubic decimeter. How many kilograms does the cut piece of steel weigh?
从一根截面直径是5分米的圆柱形钢材上截下3米，每立方分米钢重7.8千克，截下的这段钢重多少千克？
<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">(5/2) ** 2</gadget>
<output>25/4 = around 6.25</output>

<gadget id="calculator">7.8 * 3.14 * (25/4) * 3 * 10</gadget>
<output>4_592.25</output>

<result>4_592.25</result>