How to write the set of rational numbers in Latex !

Set of rational numbers

In old books, classic mathematical number sets are marked in bold as follows

$\mathbf{Q}$ is the set of rational numbers.

So we use the \ mathbf command. Which give:

$\mathbf{Q}$ is the set of rational numbers.

You will have noticed that in recent books, we use a font that is based on double bars, this notation is actually derived from the writing of classic sets on the blackboard: indeed, on the blackboard we do not fill these sets, or it would take a ton of chalk !!! In Latex, we use the amsfonts package In the preamble we have:

\usepackage{amsfonts}

and \mathbb command

$\mathbb{Q}$ is the set of rational numbers.

$\mathbb{Q}$ is the set of rational numbers.