Wolfram Research
Wolfram Math World: Sum
This page gives a complete discussion of the advanced applications of the summation operation in mathematics. Provides information about sigma, or summation notation, a manner of writing sums and how to manipulate them. The site also...
University of California
Uc Davis: The Algebra of Sigma (Summation) Notation
This page introduces the use of the sigma, or summation, sign. Also provides the properties of summation and gives answers to fourteen good learning exercises.
Paul Dawkins
Paul's Online Notes: Calculus I: Summation Notation
The tutorial reviews summation notation. Topics discussed are the properties and formulas for summation notation. Class notes, definitions, and examples with detailed solutions are included. The notes are available in pdf format.
Mathematics Archives
Math Archives: Summations
University of Tennessee provides this tutorial site explaining summations and how to evaluate them on a TI(85-86) calculator.