deletions | additions       diff --git a/laws-summation.tex b/laws-summation.tex  index 2e2d78f..3410d81 100644  --- a/laws-summation.tex  +++ b/laws-summation.tex 
...
\item $\displaystyle\sum_{n=s}^t f(n) + \sum_{n=s}^{t} g(n) = \sum_{n=s}^t \left[f(n) + g(n)\right]$  \item $\displaystyle\sum_{n=s}^t f(n) - \sum_{n=s}^{t} g(n) = \sum_{n=s}^t \left[f(n) - g(n)\right]$  \item $\displaystyle\sum_{i=m}^n 1 = n - m + 1$  \item $\displaystyle\sum_{i=1}^n \frac{1}{i} = H_n$, where $H_n$ is the nth harmonic number.  \end{enumerate}