For those who like reading about mathematics, I recommend W.W. Sawyer's books.
Some titles of his are:
Prelude to Mathematics
http://www.amazon.com/Prelude-Mathematics-W-Sawyer/dp/0486244016/ref=ntt_at_ep_dpt_1
Mathematician's Delight
http://www.amazon.com/Mathematicians-Delight-Dover-Science-Books/dp/0486462404/ref=ntt_at_ep_dpt_3
An Engineering Approach to Linear Algebra
http://www.amazon.com/gp/product/0521093333/ref=s9_simh_gw_p14_d0_i2?pf_rd_m=ATVPDKIKX0DER