Roll a piece of rectangular paper with a length of 20cm and a width of 15cm into the largest cylinder, what is the lateral area of the cylinder in cm**2.
用一张长20cm，宽15cm的长方形纸卷成一个最大的圆柱，这个圆柱的侧面积是多少cm**2．
<gadget id="calculator">20 * 15</gadget>
<output>300</output>

<result>300</result>