This paper deals with the results of students during the preparing courses of mathematics for entrance exams at an university. These courses take place every year and since the Covid-19 period, they are not only face-to-face, but also online. The study involves students of secondary schools who apply to the university of economics. This report compares results of tests of two different classes of these students and from different parts of mathematics. These tests are in the form of online quizzes. We do not prove if there are differences between the scores of students of short-time or long-time courses. In addition, we compare the results with the students from the year before. We also emphasize the more problematic topics of mathematics.