%%
%% The LaTeX Companion, 3ed
%%
%% Example 3-4-21 on page I-191 in "dashundergaps --- Produce fill-in forms".
%%
%% Copyright (C) 2022 Frank Mittelbach
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3c
%% of this license or (at your option) any later version.
%%
%% See https://www.latex-project.org/lppl.txt for details.
%%

\documentclass{tlc3exa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{183.0pt}
\sloppy
%StartShownPreambleCommands
\usepackage{dashundergaps}
\dashundergapssetup{widen, dash, gap-font = \itshape,
    teacher-gap-format = underline, gap-number-format
      = \textsuperscript{\normalfont/\thegapnumber/}}
\newcommand\puzzletext{The initial `E.' in Donald
  E. Knuth's name stands for \gap{Erwin}. The
  well-known answer to the Ultimate Question
  \gap{of Life, the Universe, and Everything} is
  42 according to \gap{Douglas Adams}.\par}
%StopShownPreambleCommands

\begin{document}
\puzzletext
\bigskip \setcounter{gapnumber}{0} \TeacherModeOn
\puzzletext
\end{document}