A cylindrical water tank, if a cylindrical iron rod with a bottom radius of 5 cm is put into the water (no water overflows), the water level will rise by 9 cm; if the iron rod is pulled out of the water surface by 8 cm vertically, the water level will fall 4 cm. Find the volume of this iron rod. (π takes a value of 3.14)
一个圆柱形水槽，若把一根底面半径是5厘米的圆柱形铁棒全部放入水中(没有水溢出)，则水面上升9厘米；若把铁棒竖着拉出水面8厘米，则水面下降4厘米．求这根铁棒的体积．(π取值3.14)
<gadget id="calculator">8 / 4</gadget>
<output>2</output>

<gadget id="calculator">5 * 5 * 3.14 * 2</gadget>
<output>157</output>

<gadget id="calculator">157 * 9</gadget>
<output>1_413</output>

<result>1_413</result>