The given situation is perfect for a do-while loop to avoid the need to read from stdin in more than one place...

{ my $count = 0;
  do
  { print "\nPlease enter a number: ";
    $in[$count++] = <STDIN>;
  }
  while ( $in[-1] !~ m/q/i );
  pop @in;  #  Remove 'quit signal'
}
chomp @in;
[download]

...but i would personally prefer something like...

while ( 'reading...' )
{ print "\nPlease enter a number: ";
  my $in = <STDIN>;
  do { push @in , $in; next; } unless $in =~ m/q/i;
  last;
}
chomp @in;
[download]