Ok so I have done around 1.5 years of maths, science and engineering classes (12 subjects) and realised I didnt enjoy engineering (my major), so I have now changed from a bachelor of electrical engineering to a bachelor of science. Now I am want to include a maths major in the degree however I essentially skimmed through the engineering maths courses that I did. One was a calculus/matrix algebra course with a smattering of statistics which I scored a credit in, another a multi-variable calculus course and some stats(distinction). The third was half vector calculus/complex analysis and half quantum physics(pass, ignored the quantum physics as much as possible). Now I am wondering should I keep these units as credit towards my maths major or start from scratch and give it my all? I really do feel I missed out on alot of the underlying theory of the mathematics I learnt and I don't like that. I have changed to another university with an alright maths department. However this was mostly my fault for not sitting down and learning the material indepth. Is it stupid to delay my graduation by not taking any maths subjects from my 1.5 years of engineering when it would increase my time till graduation by say half a year?