A cylindrical measuring bucket has a bottom radius of 5 cm. When a piece of iron is taken out of the measuring bucket, the water level drops by 3 cm. What is the volume of the piece of iron?
一个圆柱形量桶，底面半径是5厘米，把一块铁块从这个量桶里取出后，水面下降3厘米，这块铁块的体积是多少？
<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">3.14 * 25 * 3</gadget>
<output>235.5</output>

<result>235.5</result>