Recent renaissance of nuclear industry came along with a renewed interest in basic research and development activities in the field. Aiming at one of the most fundamental topics, this book takes a look at neutron transport from the viewpoint of computational mathematics. Mathematical basis of the theory is established first, including the rigorous setting of two main problems of steady-state neutron transport - the core criticality and fixed source calculations. Discretization of the governing equation with respect to energy, direction of motion and space is described next, leading to a numerical method readily programmable on a computer. An important factor guiding the selection of presented methods has been their simple applicability to enhancing existing diffusion codes which, may no longer be suitable for solving current problems with more significant transport effects. The multigroup SP3 finite volume method is derived in detail and practically demonstrated on numerical benchmarks at the end. The book may be very useful to researchers facing the task to upgrade a legacy diffusion code, but may also well serve as a concise overview of modern transport-theoretical techniques.