The radius of the base of the cylinder is doubled, and the height is also doubled, so the volume of the cylinder is enlarged to the original volume.
圆柱体的底面半径扩大2倍，高也扩大2倍，圆柱的体积就扩大到原来的多少．
<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<result>8</result>