Some identical unit cubes are used to construct a three-dimensional object by gluing them together face to face.
Sketches of this object are made by looking at it from the right-hand side, from the front and from above. These sketches are called the side elevation, the front elevation, and the plan view respectively.
This is the side elevation of the object.
This is the front elevation of the object.
This is the plan view of the object.
How many cubes were used to construct the object?