The purpose of this paper is to investigate the affordances of the e-assessment system Numbas from an Activity Theory perspective. The study follows a qualitative research design combined with semi-structured interviews with six students and two teachers. The findings reveal that the students were able to perceive and actualise several affordances of Numbas, such as ease of use and navigation and possession of facility to contain mathematical knowledge. The participants acknowledged that Numbas affords variation in mathematical contents and support for the development of pen and paper skills. Numbas also affords learner's autonomy and motivation to engage in mathematical problem-solving. Findings further show that Numbas promotes formative assessment. This can be seen from the high level of affordance perception and actualisation amongst students and teachers. [For the full proceedings, see ED636095.]