There is a cylindrical glass tank with a bottom diameter of 2 decimeters, which is not filled with water. Put an iron ball in it. When the iron ball completely sinks into the water, the water level rises by 3 cm. Find the volume of the iron ball.
有一个圆柱玻璃缸，底面直径2分米，未盛满水，放入一个铁球，当铁球完全沉入水中之后，水面升高3厘米，求铁球的体积．
<gadget id="calculator">2 * 10</gadget>
<output>20</output>

<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">3.14 * 100 * 3</gadget>
<output>942</output>

<result>942</result>