Cross-linguistic research with children has demonstrated that language – specifically, the way numbers are named – can influence the way we process numbers. In languages such as Dutch or German, two-digit numbers above twenty are reversed: The unit is named first, followed by the decade (e.g., 92 is in Dutch “tweeënnegentig” or <two and ninety>). This is known as the “inversion property” and it has been shown to negatively affect children’s numeracy and overload their Working Memory. But do these negative effects disappear with development? In this talk, I will present our work on the effects of the inversion property on adults’ basic numeracy skills.