Radical constructivism and Piagetian's scheme theory were used as epistemological and psychological assumptions to conceptualize this study. Using this conception, the author hypothesized that number concepts are composite units. The meanings of number words used by kindergarten pupils were classified into two levels: (1) preconception of number and (2) initial number concepts. Semi-structured teaching protocols were used to interview children and to collect data on their ideas about numbers. Chin-Han's reactions to solving number problems were gathered and the conceptual analysis of his meanings of number words are reported in this case study. The results revealed that Chin-Han was at the stage of initial number concept.