'Formal' Brain Fitness and/or Math

These links connect to brain fitness.
So do Algebra, SAT Prep and Decimals ;)
http://www.huffingtonpost.com/alvaro-fernandez/top-11-books-for-brain-he_b_157062.html

http://www.brainrules.net/the-rules
http://www.lumosity.com/info/company/about