Arithmetic requires the use of multiple cognitive processes, such as short-term memory (STM). However, findings on the association between STM and simple multiplication solving are mixed, potentially due to large interindividual differences in multiplication proficiency within and between samples. The present study aims to explore further the relationship between visual and verbal STM and simple multiplication solving with a large Malaysian sample (N = 230). Adults (age = 17-42) completed an online production-based multiplication-solving task, STM measures (verbal and visuospatial STM tasks), and a demographic survey. A mixed-model analysis found that verbal STM and visual STM predict multiplication performance, with lower span participants having longer reaction times during multiplication solving. Interestingly, we also observed the relationship between verbal STM and multiplication was moderated by interference, the impact of verbal STM was stronger in high-interference problems, while the visual STM-multiplication relation was moderated by problem size, high visual span participants took more advantage of their visual STM when presented with large size problems. Thus, our findings show that both verbal and visual STM in interaction with problem properties predict simple multiplication solving in adults. Hypotheses on the concrete mechanisms involved in these relationships are discussed. (PsycInfo Database Record (c) 2024 APA, all rights reserved).