Dwemish Hi-An was an aspect of the Vulcan civilization. Dwemish Hi-An was part of the formal training a young member of the race took during their path to adulthood. This rite involved identify isolation as well as brain control with number systems and equations. In addition, the child learned multiplication, left to right. Sarda was expected to have completed this during his childhood. (TOS - Fortunes of War novel: Battlestations!)