The biggest difficulty we encounter while doing scientific calculations is that the problem we are trying to solve is complex and sometimes cannot be solved analytically. Especially when evaluating our work, we need the numerical results we will obtain from scientific calculation methods in order to be able to comment. When it comes to numerical solutions, computers come into play and allow us to make calculations more easily and quickly. It should not be forgotten that the basic function of computers that do almost all of our work today is to make calculations. In order to make these calculations quickly and easily, the way we will communicate with the computer appears as different applications. Considering the similarities and differences between the applications, it is possible to do the same job using different applications. While determining the content of this book, it was aimed to provide the basic information required for the solution of linear equation systems, interpolation, extrapolation, curve fitting, numerical derivative and numerical integration methods, which are techniques used in scientific calculation, and to provide a small but useful guide for solving them with computers. It was tried to give the points we should pay attention to when doing the same operation using different applications, and it was thought to serve as a basic Rosetta stone between the applications.