  An isometric path between two vertices in a graph $G$ is a shortest path
joining them. The isometric path number of $G$, denoted by $\ip(G)$, is the
minimum number of isometric paths needed to cover all vertices of $G$. In this
paper, we determine exact values of isometric path numbers of complete
$r$-partite graphs and Cartesian products of 2 or 3 complete graphs.
