*Result*: Distinct ordinal representations mediate the influence of cardinal knowledge on Preschoolers' arithmetic performance.

*Ordinal knowledge plays a foundational role in early mathematics, yet little is known about how different forms of ordinal representation support preschoolers' arithmetic. The present study investigated whether two types of count-list-based ordinal representations-rote counting and number ordering-mediate the relationship between symbolic cardinal knowledge and arithmetic performance in preschool children. Sixty-four preschool children (mean age = 67.3 months) completed a battery of tasks assessing cardinality, rote counting, number ordering, and arithmetic. Mediation analyses revealed that both rote counting and number ordering fully mediated the relationship between symbolic number comparison and arithmetic performance. Importantly, analyses showed that these mediators differentially supported arithmetic depending on problem complexity: rote counting was more strongly associated with simpler addition problems, while flexible number ordering predicted performance on more complex addition problems typically solved with overt counting strategies. These findings highlight the heterogeneous nature of ordinal representations and underscore their role as early supports for arithmetic, even before elementary school. Implications for understanding early ordinal representations and its use on education practices are discussed.
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*Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.*