Maths

• http://en.wikipedia.org/wiki/Radix
• http://threesixty360.wordpress.com/2009/06/09/ethiopian-multiplication/ [1]

• http://www.greenteapress.com/thinkbayes/
• http://betterexplained.com/articles/linear-algebra-guide/

Software

• Mathics is a free, general-purpose online computer algebra system featuring Mathematica-compatible syntax and functions. It is backed by highly extensible Python code, relying on SymPy for most mathematical tasks and, optionally, Sage for more advanced stuff.