Monte Carlo simulation of argon cluster evaporation is in reasonable accord with molecular dynamics computations. The new Monte Carlo algorithm is based on assumptions of ergodicity and mixing. Our results affirm these statistical assumptions for argon cluster dynamics. Observations of algebraic long time decay in evaporation lifetime distributions are also in support of the assumptions. The Monte Carlo algorithm provides an easily implemented statistical approximation to decay dynamics in many degree of freedom systems. It is formulated for application to any sequential unimolecular decay process.