What is the volume of a cylinder whose base radius is 4 cm and whose height is 5 cm?
一个圆柱体，它的底面半径是4厘米，高是5厘米，它的体积是多少．
<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<gadget id="calculator">3.14 * 16 * 5</gadget>
<output>251.2</output>

<result>251.2</result>