math-sigma-notation.html
* created: 2025-06-17T17:23
* modified: 2025-09-20T15:00
title
Sigma Notation
description
The sigma notation is used as a short form of iterating expressions. It is represented by a start, end and an expression.
Summing stuff
It's basically a for loop with a starting and an end condition that executes a predefined logic n times.
\sum_{j=1}^{200} j = 20100
In this example we would start iterating at 1 (j=1), for 200 iterations, each time adding 1 to our count j until we reach j=200.
The Little Gauss
\sum_{j=1}^{200} j = \frac{200(200+1)}{2} = \frac{40200}{2} = 20100