Consider the problem of partitioning a group of b indistinguishable objects into subgroups each of size at least X and at most u. The objective is to minimize the additive separable cost of the partition, where the cost associated with a subgroup of size j is c(j). In the case that c(.) is convex, we show how to solve the problem in O(log u) steps. In the case that c(.) is concave, we solve the problem in 0(min(X, b/u, (b/k)—(b/u), u—X)) steps. This problem generalizes a lot—sizing result of Chand and has potential applications in clustering.