A rectangular cardboard is 6 cm long and 4 cm wide. If it is rotated around its axis of symmetry, what is the volume of the smallest cylinder obtained in cubic centimeters?
一张长方形硬纸板长6厘米，宽4厘米，如果以它的对称轴为轴旋转一周，得到的最小圆柱体的体积是多少立方厘米．
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

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

<gadget id="calculator">3.14 * 4 * 6</gadget>
<output>75.36</output>

<result>75.36</result>