There is current interest in how we are able to make an estimate of the approximate number of objects in a scene: existing evidence suggests that we may have a dedicated "visual number" sense that may even be linked to mathematical ability. In this talk I will present evidence from my lab that, contrary to this position, human sense of number is not independent of our sense of space/distance and that our ability to estimate one depends on the other. This implicates a common perceptual mechanism, and we describe one candidate based on the operation of neurons in the primary visual areas. This rather simple model can explain a range of perceptual phenomena associated with approximate number estimation.