Dig a cylindrical reservoir with a depth of 5 meters and a bottom diameter of 4 meters. What is the volume of the reservoir?
挖一个深5米，底面直径为4米的圆柱蓄水池，该蓄水池的容积是多少．
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

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

<gadget id="calculator">3.14 * 4 * 5</gadget>
<output>62.8</output>

<result>62.8</result>