In this paper we discuss individual numeracy practices of older people (age cohort 65 and above), concentrating on findings concerning interdependencies of numeracy practices and vulnerability and their reciprocal effects, drawing on first results of a qualitative, explorative study entitled 'Numeracy as social practice in the course of time'. For this paper, we examine the issue of vulnerability in relation to dimensions such as financial and economic situation, health and social embeddedness. Drawing on the concept of 'numeracy as social practice' according to Baker and Street (International encyclopedia of adult education and training, Pergamon Press, Oxford, 1996), we focus on the strategies of older people using numeracy practices and skills to lead independent, self-determined and autonomous lives, to experience individual life satisfaction and to avoid vulnerable situations. The findings, derived from in-depth interviews with the above-mentioned cohort, show that various meanings are attributed to numeracy practices in response to certain requirements and needs concerning personal well-being, as well as anticipating developments such as biographical transitions. We discuss how mathematical knowledge and skills are applied when transformed into individual numeracy practices. Our findings, which demonstrate the creative and meaningful use of numeracy practices according to personal needs, are then discussed within the scope of formal teaching and learning processes in basic adult education.