Learning mathematics requires the development of crystal clear concepts, and sufficient amount of practice. Hence, it is certainly possible to learn mathematics online. However, at times, a student might find himself/herself stuck at a particular problem. Even though a solution might be available, understanding it could be quite a challenge. These are the only problems that a student of mathematics might face on the internet.
One might join mathematics forums to discuss the solutions to difficult problems like these, though. The ease of learning however depends on one’s own preferences. While some students prefer to learn from teachers live, others like to learn in the comfort of their room.