scaled drawings with blender


I am a new user with blender. I need to draw some scaled shapes as in AutoCAD. For example I want to draw a line from (0,0,0) to (5,5,5). Or I want to draw a rectangle that’s up-left corner stands on (0,0,0) and down left corner stands on (-5,0,0) and so on. What is the practical way to do this? I always use scale (S). But I think there is another way.

quite easy to do!
Add the Plane object ( Top view) and enter Edit Mode.
Press N key ( Transform shelf) then select one vertice at a time and enter the desired location in the X,Y, Z fields ( Global)
You can add more verts ( LMB+Ctrl key) or delete with X key!
In Blender your “down left corner” will be 0 -5 0