Understanding number concepts and basic mathematical skills is important for many everyday activities in modern societies. Little is understood about the numeracy abilities of people with Down syndrome. At present, it appears that numeracy is an area of relative difficulty and that progress with more complex mathematical understanding is slow. However, some teaching approaches that seek to utilise certain relative strengths to communicate number concepts seem to be useful in practice. Further research is needed to define the precise difficulties experienced by children with Down syndrome and to evaluate teaching strategies.