How can I get started doing math for fun? My math teacher says that they do math for fun, and I wonder how they do that? I want to do math in my free time. Where can I find problems to solve that will engage me and will take a while to complete?
 A: Not directly responding to your question about sources, but an important bit of advice, I think: to have fun, do not pay any attention to anyone's judgement on the prestige or coolness or whatever of whatever you want to do. When you are doing math for fun, you yourself are the sole arbiter and judge of what is "good" or not!!!
In fact, I'd recommend the same for professionals, but it's more complicated.
A: Dive in! Pick a problem or two here every day and try to work through them. Read and work through solutions to others.
A: I would say I do the same thing. After finishing my A-levels (UK 18yo exams if your not familiar) I continued looking into concepts I found interesting, and websites like this are good as you can find problems and try to solve them, and if you can't someone else likely can so you learn from their answers. There are lots of cool obscure theorems too which I love finding. As others have mentioned, there are also online courses (some free) to take you beyond what you learn at school. Personally, I have found the maths I have learn on my own much more interesting than anything I was taught at school, but It is a good building block.
