I hope this is a good place to ask the question.
My issue is that I have finished high school a number of years ago, and although I did some (non-advanced) math courses then, I did not do an exam in maths for the final high school matriculation exam. Now, years later, I would like to enter a university course for computer science, but all of the programmes of interest to me require sufficient knowledge of maths as an admissions criterion. Theoretically I could go back to supplement my matriculation exam with an advanced math grade, but this is quite a bureaucratic and logistical hurdle since I live abroad and it would take a couple of years to officially pass all the courses. I am confident in being able to self-study the curriculum with support from online resources, but the issue is how to prove my knowledge to the admissions people.
I would really appreciate it if someone could let me know whether there are any certificates or qualifications for high school maths, accepted either internationally or in Europe, so that I could attend just one big exam instead of trying to organise how to sit all the 10+ individual courses and the big exam in a high school in my home country.