[bgutierrez]

Prelude to Mathematics by W.W. Sawyer was written to give students an overview of modern math concepts beyond algebra. Topics include non-euclidian geometry, linear algebra, projective geometry and group theory. Again, for someone with an understanding of algebra. I enjoyed it and think it's in the spirit of what you're looking for.

Edit: Introduction to Graph Theory by Trudeau is another that I really liked. Very little was applicable to graphs as programmers think of them. Pure math that is easy to grasp and enjoy.

[agentultra]

I came to add add Introduction to Graph Theory and found it here. I second it! A nice book and I appreciate it's funny introduction as a book designed for liberal arts majors injured by the pedagogy of institutional mathematics (paraphrasing).

If you have a grasp of algebra and sets this book is an easy read for the curious or mathematically immature.

Edit WhatIsDukkha is correct and their suggestion better reflects what I intended to say.

[WhatIsDukkha]

Innumerate is infrequently used but it's analogous to calling someone illiterate. Someone that can't do their sums.

Usually saying someone isn't "mathematically mature" ie able to read and use proofs is what you would want to say.

[bjornsing]

You can do a lot of graph theory without being able to sum integers. No problem. :)