KS test evaluating the similarity of the η Cha mass distribution with the log-normal system IMF. The comparison is done considering three mass ranges, in order to assess which parts of the distribution are alike. We progressively added ten stars in η Cha data set, selected randomly from the IMF within the mass range [0.01;0.15] M_⊙. Each time a star is added we compute a probability from the KS test. This process is repeated for the mass ranges [0.15;1] M_⊙ and [1;4] M_⊙.