Purpose: This study focuses on examining how individual differences, including biological, linguistic, and cognitive traits, and prosodic focus affect the computation biases and reaction time (RT) associated with quantity scalar terms in Mandarin-speaking children aged 3-8 years. Method: The participants of this study were 27 Mandarin-speaking children aged 3-8 years. They completed a computer-based sentence evaluation task, and their receptive vocabulary, nonverbal IQ, and theory of mind (ToM) skills were assessed. Additionally, parents provided insights into their children's executive functions, including working memory, planning, regulation, and inhibition abilities, through a questionnaire reflecting daily performance. Results: Mandarin-speaking 3- to 8-year-olds showed pervasive quantifier semantic biases versus bimodally distributed ad hoc semantic/pragmatic biases. Their quantifier pragmatic bias increased with age, working memory, and planning abilities but decreased with first-order ToM. In contrast, their ad hoc pragmatic bias improved with second-order ToM, working memory, planning, and inhibition abilities but decreased with age and receptive vocabulary. Prosodic focus reduced the number of hesitators and minimized the RT differences between hesitators and pragmatic/semantic responders. Conclusions: Children show a higher overall pragmatic bias in ad hoc compared to quantifier scalar terms, alongside notable individual differences. Quantifier and ad hoc scalar terms appear to have different initial interpretations, with the former leaning toward a semantic interpretation and the latter toward a pragmatic one. Prosodic focus reduced hesitation and encouraged further processing, although it did not significantly alter interpretation biases. Future studies should employ larger sample sizes and implicit measures to further explore these findings.