- George Polya - How to Solve It
Interesting book on proofs and a logical approach to problem solving. Original title was "School of Thinking"…
- Lancelot Hogben - Mathematics for the Millions - Silvanus P Thompson - Calculus Made Easy
Two older books that came well recommended (have been mentioned in this thread already). Not sure if that's due to the readers or their teachers nostalgia or well founded yet.
- The Manga Guide to Calculus
Erm, yeah. (I did like the Manga Guide to Databases, though)
- Benjamin & Shermer - Secrets of Mental Math
How to do mental arithmetics quickly. Good for igniting the spark and impress your friends…
Also, some book on mathematics by Russian, who employ some different methods in teaching, but I can't find the book nor its title right now, must be in some moving box. (Generally, talk to Russians. They're creepy when it comes to maths and chess)
Calculus Made Easy by Silvanus Phillips Thompson
http://www.gutenberg.org/ebooks/33283
P.S. Gave you an upvote. Just would have preferred to know the title / have a pointer to a non-PDF reference since one was available.
I like the math part of The Art of Computer Programming (in the first book) by D. Knuth. It has exercises with solutions and, as the name says, is orientated towards maths useful for programming. Plus, it's a good read. The whole series came highly recommended, but I'm still in the first part, so I can't judge it yet. ^^
Of course the way of learning I suggest is not easy or fast, especially for someone who is busy with a full time job, but I guarantee that if you do it you will build for yourself some solid grounds, and you will feel yourself more intelligent.
Out of interest, I am curious why you need to become better at maths.
So head to khanacademy.org, start with algebra and work on all exercises. Then go to the other subjects.
I highly suggest you pick one particular graduate level math subjects and sounds interesting to you and make that your goal.