LaTeX.org

The first about 30 characters in ASCII are not-printable and only for controlling devices, to ring a bell for example. One of those characters was, somehow, introduced into your document and LaTeX did not know what to do with it. If you are interested in why control characters exist and what they ...

your invalid character is already in the input:

\begin{multicols}{2}

starts with a control character (14h, what was known as Device Control 4, whatever that was used for)

\documentclass{scrartcl}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{multicol}
\begin{document}
\begin{multicols ...

Hi there,

i'm new here, and i'm new with latex :)

but i want to create an formulary with latex, and i've little trouble...

i'm trying to make it with multicols but i've there always in the output invalid chars.. can you help me?

this is the code:
\documentclass{scrartcl}
\usepackage{amsmath ...