Document possessing simultaneously text in single column and double column;

Question

I would like to make a list of math exercises. Formatting that intend this list is as follows. The first half of the page I would write in a single column. From the second half of the page into two columns I write normally.

Is there any resource (package LaTeX command or setting in the preamble of the LaTeX document) to write a document possessing simultaneously (and even on the same page) text in single column and double column?

Answer 1

the multicol package allows switching column number mid page or using standard twocolumn you can use

\twocolumn[single column material at top of this page] ... two column stuff....