If an iron ball is submerged in a bucket with a bottom radius of 5dm, the height of the water rises from 3dm to 3.2dm. What is the volume of this iron ball?
把一个铁球浸没在一个底面半径是5dm的水桶里，水面的高度由3dm上升到3.2dm．这个铁球的体积是多少？
<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">3.2 - 3</gadget>
<output>0.2</output>

<gadget id="calculator">3.14 * 25 * 0.2</gadget>
<output>15.7</output>

<result>15.7</result>