This paper is only for reviewing a formula using in a particular subject. We have known a false assumption is an assumption as a kind of logic fallacy. And we have also known that false assumptions would produce incorrect results. Incorrect results cause to be incorrect decisions. In this paper, we propose a little but important problem that calculating on a false assumption of total communication time for distributed query processing within the distributed database environment. To understand our paper, we must first explain the basic knowledge of a distributed database system. A distributed database system consists of a collection of sites, connected together via some kind of communication network. In the distributed query processing there is two or more sites that may be included. The primary objective in distributed systems is to minimize the number and volume of messages between the participant sites. There will be many possible ways of moving data around the system to satisfy the request. To minimize the network utilization, it is important that an efficient strategy be found. There may be many possible strategies for processing the request. To evaluate which strategy is to be efficient, we will calculate the total communication time for each strategy by using the formula. The choice of the best strategy is based on the result of we calculated. So, if we must have the correct answer, then we can make the correct choice. In this paper, we will apply a formula that is teaching now in our university to calculate the total communication time. We would like to present our paper with two aspects, one is ‘the false assumption on the formula that we used’ and the second is ‘suggested for that formula with another view’.