The top panel shows the distribution of the masses of the most massive star in each cluster, with the median value indicated, for the 1000 simulated clusters of 300M_⊙ each. These median values are close to the maximal value suggested by Larson (1982). Even for a cluster with 300M_⊙ of stars, the random sampling effect is huge. The bottom panel shows the total cluster luminosity as a function of the mass of the most massive star, for the three IMFs indicated by their color. The line shows the luminosity of the single most massive star in the cluster. We can see (1) that the luminosity of a 300M_⊙ cluster can vary by a factor 1000 and (2) how important the most massive star is for the total zero-age luminosity as when a very massive star is present, it dominates the luminosity (and ionizing photon production) of the cluster for its lifetime.