The area of a rectangular green space is 252 square meters, the length of one side is 18 meters, the width increases to 36 meters, and the length remains unchanged. What is the expanded area?
一块长方形绿地的面积是252平方米，其中一条边的长是18米，宽增加到36米，长不变．扩大后的面积是多少？
<gadget id="calculator">36 * 18</gadget>
<output>648</output>

<result>648</result>