In jainism, why Navakar Mantra is considered as Maha mantra?

Question

Why there is difference between 5 and 9 sentences [pad] in the Navakar itself?, Is there any logic for the order or sequence of these sentences?

Answer 1

Navakar Mantra, also called the Namokar Mantra or the Namaskar Mantra, is the most important prayer used in Jainism.

णमो अरिहंताणं
णमो सिद्धाणं
णमो आयरियाणं
णमो उवज्झायणं
णमो लोए सव्व साहूणं
एसो पंच णमोक्कारो, सव्व पावप्प णासणो
मंगलाणं च सव्वेसिं, पढमं हव इ मंगलं
Namo Arihantânam I bow to the Arihantâs.
Namo Siddhânam I bow to the Siddhâs.
Namo Âyariyânam I bow to the Âchâryas.
Namo Uvajjhâyanam I bow to the Upadhyâya.
Namo Loe Savva Sahûnam I bow to all the Sadhûs.
Eso Panch Namokkaro, Savva Pâvappanâsano
Mangalanam Cha Savvesim, Padhamam Havai Mangalam

This fivefold bow mantradestroys all sins and obstacles
and of all auspicious mantras, is the first and foremost one.

In the prayer, Jains salute the virtues of the Pancha Parmeshti, or five benevolents: The Arihants, Siddhas, Acharyas, Upadhyayas, and normal monks. They do not pray to a specific Tirthankar or monk by name. By saluting them, Jains believe they receive the inspiration from the five benevolent for the right path of true happiness and total freedom from the misery of life. Jain prayers do not ask for any favors or material benefits from the Tirthankaras or from sadhus and sadhvis. These prayers simply serve as a gesture of deep respect towards beings they believe are more spiritually advanced and to remind followers of the Jain religion of their ultimate goal of nirvana or moksha.

Digambars and Sthanakvasis only use the first five lines, and in inscriptions inside the Orissa Hathi Guffa caves, the order is different from what is given above.-

Answer 2

णमो अरिहंताणं
णमो सिद्धाणं
णमो आयरियाणं
णमो उवज्झायणं
णमो लोए सव्व साहूणं

The Navakar Mantra in english is:

I bow to the Arihantâs.
I bow to the Siddhâs.
I bow to the Âchâryas.
I bow to the Upadhyâya.
I bow to all the Sadhûs.

the 5 sentences are the most important because Jains salute the virtues of the Pancha Parmeshtin, or five spiritual masters. When it is 9 sentences you add these three lines(i will jsut put in english):

This five-fold salutation
Destroys all sins
And amongst all auspicious things
Is the most auspicious one

and it just to give extra importance to the spitrual masters.