A modelling is a powerful tool developing and testing theories and is applied to many different fields of study. Modelling together with simulation combines general methodological developments to many specific applications. Numerical methods are those problems where the mathematical problem has been reformulated enabling it to be solved using mathematical operations. A good example of the usefulness of computer simulation can be found in automobile traffic simulation, grocery stores checkout lines, inventory management, stock prices predictions and environmental consequences of policies. The formula and functions that are used may not provide an accurate description of the system resulting in inaccurate output from the simulation. Simulation can be used to compress a time frame, a simulation model run on a computer system can be used to investigate quickly the effects of a change in a real-life situation that take place.