The optimal stopping rules with multiple selections of $m \ge 1$ objects with the objective of maximizing the probability of obtaining the best object are studied for two problems with an unknown number of objects: the problem with a random number of objects, and the problem where the objects arrive according to a homogeneous Poisson process with unknown intensity $\lambda$. These two problems are variation of the so-called secretary problem. This article introduces an easier method based on the one-stage look-ahead function (defined herein) depending on $m$ and its recursive relation to the number $m$, to find the optimal stopping rule for all $m$, without a direct solution of equations suggested by a common dynamic programming approach.