Mantras are typically repeated hundreds or even thousands of times. The japa mala is used so that one can focus on the meaning or sound of the mantra rather than counting its repetitions. One repetition is usually said for each bead while turning the thumb clockwise around each bead, though some traditions or practices may call for counterclockwise motion or specific finger usage. When arriving at the head bead, one turns the japa mala around and then goes back in the opposing direction. There are typically knots between each bead. This makes using the japa mala easier as the beads will not be as tight on the string when used.
If more than 108 repetitions are to be done, then sometimes in Tibetan traditions grains of rice are counted out before the chanting begins and one grain is placed in a bowl for each 108 repetitions. Each time a full japa mala of repetitions has been completed, one grain of rice is removed from the bowl. Often, practitioners add extra counters to their japa malas, usually in strings of ten. These may be positioned differently depending on the tradition; for example some traditions place these strings after every 10th bead. This is an alternative way to keep track of large numbers, sometimes going into the hundreds of thousands, and even millions.
There are numerous explanations why there are 108 beads, with the number 108 bearing special religious significance in a number of Hindu, Buddhist and Jain traditions.
27 Constellations x 4 Padas (parts) = 108
12 Zodiac Houses x 9 Planets = 108
Upanishads or the Scriptures of the Vedas = 108
There are special qualities or characteristics of Arihantas 12, Sidhhas 8, Aacharya’s 36, Upadyayas 25 and Sadhus 27 which total to 108.
Thus, when we recite or recount number 108, we are actually remembering the entire universe. This reminds us of the fact that the universal self is omnipresent, that is the innate nature of the self.