A cylinder has a base diameter of 80 decimeters and a height of 15 decimeters, find the volume of the cylinder.
一个圆柱的底面直径是80分米，高15分米，求这个圆柱体的体积．
<gadget id="calculator">80 / 2</gadget>
<output>40</output>

<gadget id="calculator">40 ** 2</gadget>
<output>1_600</output>

<gadget id="calculator">3.14 * 1_600 * 15</gadget>
<output>75_360</output>

<result>75_360</result>