21, Not Touched Maths Since GCSE. Want to start learning again. Where to Start? I am 21 and have got into computer programming. Doing very well in my degree. Would love to get into computer science but feel I am being held back by my basic knowledge of maths. I got an A at GCSE, but failed A Level Math. I want a book aimed at adults, which will start me back where I left off - at A Level standard.
There are soooo many maths books out there. I don't have a clue which one suits me so I thought I would ask here. Can anyone recommend me a book that meets my requirements. Thank you.
 A: Converted my comment to an answer, since I ran out of space:
If your motivation is to improve your programming, then much depends on what types of programs you write. A lot of programming can be done with little or no knowledge of mathematics. And, as proof of this, the level of mathematical knowledge in many programming communities is astonishingly poor, but the code still seems to work most of the time. 
On the other hand, if you're doing graphics or game programming (for example), it will be quite useful to have some knowledge of basic linear algebra, geometry, vectors, calculus, and simple numerical methods. 
So, tell us what kind of programming you do, and where you think your maths is weak, and you'll get some more specific advice.
I have never looked at them myself, but people often recommend the Khan Academy  tutorials. 
A: 
I think the best idea would be to start off from A Level maths. This level of maths is meant to lead on from GCSE until University, so if you went through most of the UK system, you might have trouble starting other courses if you didn't finish it.
I would start from the Core 1 & 2 Cambridge book for OCR (found here ) and then go on to the Further Pure, Stastistics and/or Mechanics books depending on what you like and want to study.

Additionally, I often find that Maths Olympiads are related to Computing. You might have experience of these. You can find past papers, mentoring schemes, and books on the UKMT website. At your age, I would start from the [Intermediate Maths Olympiad], but you should try one of these and then move up or down to harder or easier Olympiads as you see fit.

I know this is a couple of years late, but I hope it will help anyway.
Good luck!
