Xiaoqiang asked for the volume of an iron ball. He put the iron ball into a cylindrical measuring cup with a bottom diameter of 10 cm and a height of 8 cm. It was completely submerged, and the water surface rose from 5 cm to 7 cm. What is the volume of this iron ball?
小强要求一个铁球的体积，他把铁球放入底面直径10厘米、高8厘米的圆柱形量杯中，完全浸没，水面由5厘米上升到7厘米．这个铁球的体积是多少？
<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">7 - 5</gadget>
<output>2</output>

<gadget id="calculator">3.14 * 25 * 2</gadget>
<output>157</output>

<result>157</result>