An operation is called broadcasting if a node sends a packet to all other nodes in an ad hoc network. Broadcasting is an elementary operation to support many applications in ad hoc networks. Thus, many schemes have been proposed for reducing the number of re-broadcasting packets. However, to the best of our knowledge, few papers discuss the bound of necessary broadcasting packets. In the work, we derive formulas for estimating the number of required broadcasting packets by taking three different approaches. In addition, we also propose two protocols: the cluster-head-early method and the connecteddominating-set method to reduce the redundant rebroadcast packets without exploiting the mechanisms of hello messages or cluster formation.