If the ground radius of the cylinder is doubled and the height remains the same, how many times will the volume of the cylinder be enlarged?
圆柱的地面半径扩大2倍，高不变，那么圆柱的体积扩大多少倍．
<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<result>4</result>