When we are solving a mathematical problem, we usually try to find a solution as exact as to the given problem as well as to find a closed form solution. Remind that It is obvious that most realistic problems do not have exact solutions. Hence, we try to simplify the orogonal problem to an approximated problem which probably has an exact or closed form solution. The simplification methods are used as an alternative approach. We will show in this article that the simplification methods have also a number of fundamental problems.