Given a gas ofN0hard‐sphere molecules in a vessel of volumeV0, one shows in a simple way that the probabilityWN0(N,V,V0) thatNmolecules are located in a subvolumeVofV0is given by the hypergeometric distribution. One shows that this distribution can be written as the product of the binomial distribution, which characterizes the ideal gas, and a factor which takes into account the size of the molecules. In the limit of low densities, one checks in two cases of practical interest that the derived distribution presents slight deviations from the corresponding ideal behavior.