Abstract: | Let $G$ be a finite group and $mathfrak{c}(G)$ denote the number of cyclic subgroups of $G$. It is known that the minimal value of $mathfrak{c}$ on the set of groups of order $n$, where $n$ is a positive integer, will occur at the cyclic group $Z_n$. In this paper, for non-cyclic nilpotent groups $G$ of order $n$, the lower bounds of $mathfrak{c}(G)$ are established. |