I started off doing a combined maths and computer science degree.
With both computer science and maths you are chronically confused. The difference being with computer science it doesn't matter so much if you don't understand something, if you can get it to work you know you are on the right track. Maths is much more progressive, each proof builds on a previous one. So if you fail to understand one step you are screwed from that point on.
After the first year I realised I didn't actually enjoy being permanently confused and so I ditched the maths to focus on computers. I do regret this. It didn't take long at all before I forgot all that knowledge I had spent years sweating over.
With both computer science and maths you are chronically confused. The difference being with computer science it doesn't matter so much if you don't understand something, if you can get it to work you know you are on the right track. Maths is much more progressive, each proof builds on a previous one. So if you fail to understand one step you are screwed from that point on.
After the first year I realised I didn't actually enjoy being permanently confused and so I ditched the maths to focus on computers. I do regret this. It didn't take long at all before I forgot all that knowledge I had spent years sweating over.