The length of a rectangular swimming pool is 21 meters and the width is 15 meters. What is the area of the swimming pool in square meters?
一个长方形的游泳池的长是21米，宽是15米，这个游泳池的占地面积是多少平方米？
<gadget id="calculator">21 * 15</gadget>
<output>315</output>

<result>315</result>