A cylindrical glass container with a diameter of 8 cm at the bottom and a height of 4 cm of water inside. A 10 cm iron rod is inserted into the water and the water surface rises to 5 cm. Find the volume of the iron rod.
一个圆柱形玻璃容器，底面直径8厘米，里面水的高度是4厘米，将一根10厘米的铁棒插入水中，水面上升到5厘米处，求铁棒的体积．
<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<gadget id="calculator">5 - 4</gadget>
<output>1</output>

<gadget id="calculator">5 / 10</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / (1/2)</gadget>
<output>2</output>

<gadget id="calculator">3.14 * 16 * 2</gadget>
<output>100.48</output>

<result>100.48</result>