# Math Help - Basic Summation

1. ## Basic Summation

Find $S_N$ where
$S_N=$ $\sum_{n=N}^{N^2}(\frac{1}{n(n+1)}$

and determine
$S_N$ when
$\lim_{N \to infinity}$

$\sum_{n=N}^{N^2}\frac{1}{n(n+1)}=\frac{1}{N}-\frac{1}{N^2+1}$
3. Your answer confuses me. Which 2 rational expressions $\frac{1}{N}$ and $\frac{1}{N^2+1}$, that gives me,
$\frac{N^2+1-N}{N(N^2+1}$