Book excerpt: The Mathematical Olympiads for the Fifth Grade of Elementary School discussed here are none other than the Open Mathematical Olympiads of the City for the 5th grade which are held every year in the city of Moscow since 2007, at the facilities of the Technological University of Russia - MIREA. These Olympiads consist of two independent rounds, one written and one oral. Likewise, the problems included here correspond to the written round, which present two levels of difficulty, of 10 and 5 problems respectively.In this workbook has been compiled all the Olympiads held during the years 2011-2020 and is especially aimed at schoolchildren between 10 and 11 years old, with the aim that the students interested either in preparing for a math competition or simply in practicing entertaining problems to improve their math skills, challenge themselves to solve these interesting problems (recommended even to middle school students with little or no experience in Math Olympiads and who require comprehensive preparation before a competition); or it could even be used for a self-evaluation in this competition, trying the student to solve the greatest number of problems in each exam in a maximum time of 2 hours. It can also be useful for teachers, parents, and math study circles. The book has been carefully crafted so that the student can work on the same book without the need for additional sheets, what will allow the student to have an orderly record of the problems already solved.Each exam includes a set of 15 problems from different school math topics. To be able to face these problems successfully, no greater knowledge is required than that covered in the school curriculum; however, many of these problems require an ingenious approach to be tackled successfully. Students are encouraged to keep trying to solve each problem as a personal challenge, as many times as necessary; and to parents who continue to support their children in their disciplined preparation. Once an answer is obtained, it can be checked against the answers given at the end of the book.