If you wish to find out the area of a construction element (e.g. a Slab with hole, pictured here), there are several ways to do it.
1. Using a Fill
Fills have the ability to display Area. So if you place a fill on top of the slab, the fill area will give you the slab area.
Check the Show Area Text checkbox in the Fill Settings Dialog or the Fill Info Box.
Then, using the Magic Wand, click the outline of the Slab to create the Fill, then place the Area Text of the Fill. Since the Slab has a hole, select the placed Fill and place a corresponding hole in the Fill using the Magic Wand method.
2. Using a Zone
Zones also have the ability to display Area information.
Set the Zone’s Construction Method to Manual.
Again, use the Magic Wand method to place the Zone. The Zone will display the area of the Slab under it.
3. Using the Element Information Palette
The Element Information Palette can be brought up using the Window > Palette > Element Information menu command.
After it appears, click the Area on Plan button in the Information Content part of the Palette.
Then select the Slab, and the desired information appears in the Element Information Palette.
The Element Information Palette is more useful than the other method because it displays Areas both with and without holes, plus it can be set to display other values (e.g. length, volume, area of vertical sides).