Areas around the intraparietal sulcus have been thought to be crucially involved in the perception of numerical information. The hosted cognitive system, called approximate number system (ANS), allows humans to extract a numerical approximation from sensory input. In this presentation, I will present a number of functional MRI studies that tested some of the basic assumptions of the ANS. In particular, I will present evidence that suggests that we flexibly use attentional resources in posterior parietal areas during the estimation of numerical magnitude. I will also provide results that challenge the idea that the IPS hosts a modality (e.g. auditory vs. visual) or mode (i.e. sequential vs. simultaneous) independent instantiation of the ANS. Together, these results call for an update of the idea that IPS hosts an abstract number code.