Xiaoming's bed is 20 decimeters long and 12 decimeters wide. A mattress of the same size as the bed is to be spread. What is the area of the mattress in square decimeters?
小明的床长20分米，宽12分米，要铺上与床大小相同的床垫，这块床垫的面积是多少平方分米？
<gadget id="calculator">20 * 12</gadget>
<output>240</output>

<result>240</result>