This small collection differs from other books of similar content, mainly in that it offers less used material, and in the way it is processed, it is closer to school arithmetic, affecting its various departments. In order not to turn a pleasant game of mind into a tedious activity, too serious for entertainment and often too fruitless for serious work, the author avoided difficult questions and selected only such material that is quite feasible for most readers. Although the book means readers who are familiar only with the elements of arithmetic, there are pages in it that are interesting, perhaps for more knowledgeable ones. A diligent request to such readers is not to refuse to inform the author about the shortcomings of the book they noticed.