Symbols, such as letters, are used in math as shorthand to represent quantities or express processes. One such symbol looks like a capitol E but is actually sigma, the 18th letter of the Greek alphabet. In math, sigma means "sum it up."
The Swiss mathematician Leonhard Euler, born in 1707, was the first person to use the sigma symbol to represent the addition of a series of math terms. He is the "father" of a number of symbols, or notation, used today in higher mathematics.
In a typical notation summation problem, the math sentence begins with the phrase including sigma topped by the number 4 and with another phrase, "k=1", underneath. "K" equals the beginning term and together with 4 indicates that the phrase equals the sum of (2k + 1) from 1 to 4.
Plug all numbers from 1 to 4 into the general term, (2k + 1) in this case, and then add the terms together.
Sigma, or summation notation, helps mathematicians identify the numbers in a series that follows a pattern, which may be lengthy, and to add them up. It is a handy way to show where the series begins and ends.