As far as brushing very very basic math skills, i'm using thisthese books:
Elements of Mathematics for Economics and Finance. Mavron, Vassilis C., Phillips, Timothy N This books covers essential math skills (addition substraction), to partial differentiation, integration, matrix and determinants, and a small chapter on optimization, and also differential equation. It's targeted to economics and finance, but it's a small book, the sequence of chapters suits my need, and easy read for me.
Statistical Analysis: Microsoft Excel 2010. Conrad Carlberg Covers basic statistical analysis, to multiple regression, and analysis of covariance, and it uses excel.
Discovering Statistics Using R. Andy Field, Jeremy Miles, Zoë Field. Have not read it yet. It uses R.
Elementary Linear Algebra. Ron Larson, David C. Falvo.
Matrix Methods: Applied Linear Algebra By Richard Bronson, Gabriel B. Costa. covers elementary linear algebra and matrix calculus
Those are the basic math books that i use to relate to data mining / machine learning
Hope this helps