The textbook presents in the most simplified form the basic theoretical provisions of set theory, number representation, combinatorics and mathematical logic, as well as ways to solve practical problems using their methods. A large number of examples are considered. There are also questions for self-control of the level of knowledge and tasks for self-solution. Meets the requirements of the federal state educational standards of higher education of the latest generation. For undergraduate and graduate students in the field of Computer Science and Computer Engineering, as well as students of other fields studying information technology. Also, the manual can be used by young specialists from the IT field in independently eliminating gaps in certain sections of discrete mathematics.