Hindu mantras are traditionally repeated 108 times, using mala beads to count the repetition. Shaivites traditionally count on rudraksha beads, whereas Vishnavites us beads made from the stems of the tulsi plant.
There are times when it is useful to chant japa without mala beads. I recently read a facebook post that described a fairly complicated way of counting to 108 using your fingers. I found this method rather confusing, so I thought that it might be useful to describe a method that I use.