The central role played by Mathematics in almost all scientific and commercial disciplines and even in sociological studies has qualified it as selective for any application to access the grandes écoles; henceforth brilliance in mathematics is essential. However, shining in mathematics requires considerable effort on the part of the student as well as vigilance and support from a specialist for the common sense of the course of acquisition of the to know and to know mathematics and, it is this support that I will assume as a specialist.