One of our favourite explanations for having 108 beads on a mala is related to the chakras (the seven energy points in our body).
It has been said there there are 108 energy lines connecting to the heart, with one of them believed to be the path to self realization.
When using your mala beads in meditation and chanting your mantra, some have said you are complete once you have done it 100 times. The 8 extra beads are to account for errors. Or even more beautiful, are meant to be an offering to your guru.
Many choose to recite their mantra in sanskrit, the ancient script of India. Within the Saksrit alphabet there are 54 letters. Each letter has a feminine and masculine version — totalling 108.