Basic rules of Mantra Shastra:
1. We have a source: the efforts that we want to utilize: Depicted by number of words of the Mantra
2. A destination: where we want to put these efforts: Depicted by the number of alphabets of the Mantra in Sanskrit language. Where ever we have half alphabet, we ignore it. It means we count the complete alphabets only.
3.Devata: the stahna or place of the Giver of Light, where the deity of the Mantra sits and protects that aspect of the native.
Very simple example is mantra
II Aum Namha Shivay II II ॐ नमः शिवाय II
Words in the Mantra: Aum (1) Namha (1) Shivay (1) = 3
Letters in the Mantra : Aum (1) Namha (2) Shivay (3) = 6
So the source is 3rd H (Dushchikya bhava or the House that creates disturbing/aggressive thoughts). Taking the sword/gun out from your waist is the thought of the 3rd H. It can be for self defense as well.
The Destinations is 6th House : Shad Ripu or the weaknesses most people posses.
The Devata is calculated by counting the number of H from the Source to the Destination and then counting the same number of H from Destination.
In our example the count from source to destination is 4 (from 3rd H to 6th H…we include the 1st H in counting) so the Devata Sthana is 4th H from the Destination (i.e. 6th H) , so with this calculation… it comes out to be 9th H ( 4th H from the 6th H).
Final Meaning: any native who is doing this mantra is putting all his initiative and aggressive thought (3rd H) in destroying all his Sins or Shad Ripu or weaknesses (6th H) by worshiping lord Shiva, who is protecting the Dharma/Righteousness of the native (9th H as He sits there).
II Aum Tat Sat II