# Thread: summation notation

1. ## summation notation

How would I go about writing $\displaystyle 1/2-1/3+1/4-1/5+1/6$ in summation notation?

2. Originally Posted by LovesMeTrike
How would I go about writing $\displaystyle 1/2-1/3+1/4-1/5+1/6$ in summation notation?

$\displaystyle \sum_{n=2}^6 \frac{(-1)^n}{n}$

The $\displaystyle (-1)^n$ term gives the alternating signs.