Sums, Subscripts and Superscripts test (LaTeX)

\[{{\sigma }^{2}}=\frac{1}{N}\sum\limits_{i=1}^{N}{{}}{{\left( {{x}_{i}}-\bar{x} \right)}^{2}}\]

Sums, Subscripts and Superscripts test (Microsoft Office equation converted to jpeg)

\[r^2\]

\[25\%\]