Economics in One Lesson by Henry Hazlitt is a good slim introduction to the economic mindset. For a different approach focused on the application of economic thinking to everyday life The Logic of Life by Tim Harford is worth a look. Neither book covers much of the math of economics but I think that is a good thing since most of the math heavy parts of economics are the least useful and relevant.

ETA: Economics In One Lesson is a heavily free market / free trade 'classical' economic slant.