We explore how numbers are represented amongst children in different cultures, and show how this can enrich our understanding of mathematical cognition. We focus on two specific, related topics; the representation of multi-digit numbers and the scaling of a mental number line. We consider whether linguistic differences in number structures directly influence children’s understanding of place value. We also consider whether cross-cultural and developmental differences in the quality of children’s mental representations of number are direct influences on mathematical skill. Together, these two topics allow us to consider evidence for the existence of cross-cultural difference in mathematics and investigate factors that might underlie them. We propose that whilst the interpretation of data needs to proceed cautiously, valuable insights can be gained from relevant research.