OMB+ and viaMINT are free online courses that are specifically designed to help students review mathematical content covered at school and prepare for their studies at university. But you do not have to be a student to take these courses.
OMB+ consists of ten sections, each of which uses a teaching text to explain the mathematical skills necessary for the section. It includes lots of examples, interactive images, exercises, and tests.
The viaMINT course offers six thematic modules in which you learn with videos, exercises, and examples. Clear explanations, interactive learning, and immediate feedback make it easy for you to brush up on your math skills.