In the process of development, Mathematics has occupied a very important position in all fields. Numerical analysis is a relatively new science that studies and deals with basic problems such as: Errors, approximation of real solutions of nonlinear equations and systems of linear equations, approximation and interpolation of functions.. In order to facilitate computation and be able to program on electronic computers, the process of solving problems is presented as an iterative procedure.The article deals with the problem of error and function approximation and the applications of interpolation polynomials in approximation as an effective tool commonly used in science and engineering.