I count on my fingers using this method:

  1. No fingers = 0, assume all values are cumulative unless stated otherwise.

  2. Start with index finger on Right hand:

  • 1 = Index
  • 2 = Middle
  • 3 = Ring
  • 4 = Pinky
  • 5 = Thumb
  1. After five, clear hand and start from Thumb and go until 9 (Ring)
  • 6 = Thumb
  • 7 = Index … etc
  1. Double digits are counted on Left hand*, following same process as 1-3.
  • For example: 13 would be:
    • Left Hand: Index
    • Right Hand: Index, Middle, Ring
  • For something like 47 would be:
    • Left Hand: Index, Middle, Ring, Pinky
    • Right Hand: Thumb, Index

Using this method, the highest you can count to is 109:

  • Left Hand: Thumb, Index, Middle, Ring, Pinky
  • Right Hand: Thumb, Index, Middle, Ring

You could also probably differentiate 5 and 10 by half-raising your thumb for 5, and full raise for 6-10.