A cardboard cylinder with a height of 150 cm is a square when its side is expanded. What is the lateral area of the cardboard cylinder?
一个高150厘米的硬纸圆柱筒，侧面展开是个正方形．这个硬纸圆柱筒的侧面积是多少．
<gadget id="calculator">150 * 150</gadget>
<output>22_500</output>

<result>22_500</result>