A cylinder expanded sideways is a square with a side length of 15 decimeters. What is the lateral area of this cylinder.
一个圆柱侧面展开是一个正方形，边长为15分米．这个圆柱的侧面积是多少．
<gadget id="calculator">15 * 15</gadget>
<output>225</output>

<result>225</result>