How about something like:

# default
$Max_Questions = $Total_Questions
  unless defined $Max_Questions;

# check boundaries
croak "Number of questions in $FileName exceeded"
  if $Max_Questions > $Total_Questions;
croak "Must have at least one question in the test"
  if $Max_Questions < 1;

# good to go
&_set_Max_Questions($self, $Max_Questions);
[download]

Update: D'oh! Corion beat me to it... but I like croak ... if better than if ... croak in this case; I think it makes it more obvious that the boundary checks are error conditions, rather than correctable "mistakes" (like undefined $Max_Questions).

Update 2: Fixed syntax error... thanks TStanley.

--
The hell with paco, vote for Erudil!
:wq