International Mathematical Forum, Vol. 17, 2022, no. 2, 75 - 87 HIKARI Ltd, www.m-hikari.com https://doi.org/10.12988/imf.2022.912315 Packing Chromatic Number of the Join of Some Classes of Graphs Alje Marie M. Urenda Bisbee High School Bisbee, Arizona 85603, USA Jacel Angeline V. Lingcong, Normina A. Batucan, Joel G. Adanza, and Michael P. Baldado Jr. 1 Mathematics Department Negros Oriental State University Dumaguete City, Philippines This article is distributed under the Creative Commons by-nc-nd Attribution License. Copyright c  2022 Hikari Ltd. Abstract Let G be a graph. A packing k-coloring of G is a function f : V (G) → {1, 2,...,k} such that any two vertices of color i are at a distance at least i + 1. The packing chromatic number of G, denoted by χ ρ (G), is the smallest integer k for which there exists a packing k-coloring f : V (G) →{1, 2,...,k}. In this paper, we gave the packing chromatic number of the join of some classes of graphs. Moreover, we characterized graphs with packing chromatic number equal to their order. Mathematics Subject Classification: 05C15 Keywords: broadcast coloring, packing k-coloring, packing chromatic number, join 1 Corresponding author