The wall in front of the classroom is 6 meters long and 3 meters wide. There is a blackboard on the wall with an area of 3 square meters. Now the wall is to be painted, how many square decimeters is the area to be painted?
教室前面的墙长6米，宽3米，墙上有一块黑板面积是3平方米，现在要粉刷这面墙壁，要粉刷的面积是多少平方分米？
<gadget id="calculator">6 * 3</gadget>
<output>18</output>

<gadget id="calculator">18 - 3</gadget>
<output>15</output>

<gadget id="calculator">15 * 100</gadget>
<output>1_500</output>

<result>1_500</result>