I have a polygon shapefile comprised of 4 polygons representing landslides (see image). None of them are overlapped. Number 1 comprises everyone (2, 3 and 4). Number 4 comprises number 3. Finally number 2 and 3 are indivual.
I've calculated the area of every individual polygon but I need to calculate the involved areas as mentioned above. Is there any possibility of adding up the areas creating a new field using the field calculator?