Latex how to write percent

Latex how to write percent % …By default percent means a comment on the tex file. How to bypass this behaviour ?

To write % symbole in LateX, you must use backslash to protect it like follows

\documentclass[12pt,a4paper]{article}
\usepackage[utf8]{inputenc}
\begin{document}
\noindent
How to write percent: $-2.5 \%$ 
\end{document}

which gives

How to write percent: $-2.5 \%$