Y. Nishiyama
2013 International Journal of Pure and Applied Mathematics  
It has been written that across the world there are 27 types of counting method using the fingers. For example, there are various methods for starting to count 'one' using either the index finger, thumb or little finger. In ancient Rome, people counted 'one' by bending their left little finger. Counting using the fingers differs according to region, ethnicity, and historical period. This chapter also discusses the 'evolutionary theory' of counting methods.
doi:10.12732/ijpam.v85i5.4 fatcat:kewrml2tlbgydn3wlpyeqy6iji