Drawing upon research, theory, classroom and personal experiences, this paper focuses on the development of primary-aged children's computational fluency. It emphasises the critical links between number sense and a child's ability to perform mental and written computation. The case of multi-digit multiplication is used to illustrate these important links. The author states that, while the path to computational fluency is not a straight-forward one for most students, is it clear that the promotion of number sense is critical to a basic understanding of mathematics and a child's ability to compute easily. (Contains 5 figures.)