Math Ref is a math reference application for the iPhone/iPad/iPod Touch, Android and Kindle that includes over 1,400 helpful formulas, figures, tips, and examples of the equations and concepts.
Google Play: http://bit.ly/15xvIFT
Math Ref Free is a free version of Math Ref. This app gives you just a sample (over 600) of the many helpful formulas, figures, tips, and examples that are included in the full version of Math Ref.
Google Play: http://bit.ly/15xw5jS