Blender python math operations on vertex I can print a vertex in Blender, but how do i do basic math operation; 
Like add multiply or divide them with other 3d coordinates ?

As here the last line doesnt work :

      for face in current_obj.data.polygons:
           verts_in_face = face.vertices[:]
           print("face index", face.index)
           print("normal", face.normal)
      for vert in verts_in_face:
           local_point = current_obj.data.vertices[vert].co
           total_points = total_points + local_point  # &lt;&lt;&lt; error here
When you initialize total_points outside the loop it should work

import mathutils
..
..
total_points = mathutils.Vector((0,0,0))

for vert in verts_in_face:
    local_point = current_obj.data.vertices[vert].co
    total_points = total_points + local_point


For all available vector operations you can lookup the mathutils docs