  Let $\Gamma$ be a group acting on a set $X$. The distinguishing number for
this action of $\Gamma$ on $X$, denoted by $D_{\Gamma}(X)$, is the smallest
natural number $k$ such that the elements of $X$ can be labeled with $k$ labels
so that any label-preserving element of $\Gamma$ fixes all $x \in X$. In
particular, if the action is faithful, then the only element of $\Gamma$
preserving labels is the identity. In this paper, we obtain an upper bound on
the distinguishing number of a set knowing the distinguishing number of a set
under the action of a subgroup. By the concept of motion, we obtain an upper
bound for the distinguishing number of a group. Motivated by a problem (Chan
2006), we characterize $D_{\Gamma,H}(X)$ which is the smallest number of labels
admitting a labeling of $X$ such that the only elements of $\Gamma$ that induce
label-preserving permutations lie in $H$. Finally, we state two algorithms for
obtaining an upper and a lower bound for $D_{\Gamma , H}(X)$.
