Statistics were not the strength of the Arabs at that time (they didn’t even bother writing their history till decades later). We donot have any exact numbers on how many were expelled in the first two expulsions, but writers like Reza Aslen agree that the number of Jews killed in the massacre of Banu Quraiza was 700-1000 (which is a big population for that time). It is universally accepted that all jews of medina were expelled killed or enslaved within a decades of the muslims arriving and taking over the city.