Not all books about math are textbooks! If you are interested in math and want something fun to read, you might want to try one of these:
Symmetry: A Journey into the Patterns of Nature - Marcus du Sautoy
The Music of the Primes: Searching to Solve the Greatest Mystery in Mathematics - Marcus du Sautoy
The Poincare Conjecture: In Search of the Shape of the Universe - Donal O'Shea
Euler's Gem: The Polyhedron Formula and the Birth of Topology - David S. Richeson
Dr. Euler's Fabulous Formula: Cures Many Mathematical Ills - Paul J. Nahin
e: The Story of a Number - Eli Maor