Sigma Notation

What is the Sigma Notation?

Sigma notation (also called summation notation) is a concise way to represent the sum of a series of terms. It uses the Greek capital letter sigma (Σ) to indicate summation.

The following diagram shows the Sigma Notation. Scroll down the page for more examples and solutions using the Sigma Notation.

Where:
Σ (Sigma): The summation symbol, indicating that we need to sum the terms that follow.
i: The index of summation or variable of summation. It’s a variable that takes on integer values within a specified range. Any letter can be used as the index (e.g., j, k, n).
m: The lower limit of summation. This is the starting integer value for the index i.
n: The upper limit of summation. This is the ending integer value for the index i. The summation proceeds until i reaches n.
xᵢ: The general term or summand. This is an expression that depends on the index i. For each integer value of i from m to n, we evaluate this expression, and then we add all these resulting values together.

Series : Sigma Notation : ExamSolutions : A-Level Maths
In this tutorial you are shown the meaning behind sigma notation for the sum of a sequence called a series.

Series & Sigma notation (1) FP1 Edexcel A-Level

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Series & Sigma notation (2) FP1 Edexcel A-Level

Sequences / Sigma Notation: C1 Edexcel June 2013 Q4

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Sequences and Series 7 - Sigma Notation Arithmetic Series

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