Why 108 beads?
There are many reasons why the number 108 is used, one being there are 108 Upanishads.The number 108 is used throughout the Chinese, Buddhist, Jain, Sikh and mentioned in Islam.
The distance of the moon to earth is 108 times the diameter of the moon, as well as the diameter of the Sun is 108 times the diameter of the earth and the distance of the sun to the earth is 108 times the diameter of the sun.
The number 108 is also devided as a mala could be too long to wear, usually in 54, 36, 27, or 9 beads. The last bead is known as the meru, or the peak and marks the end of the cycle when chanting.