I have no idea what you're trying to do, but you're missing a closing } and get rid of the &

sub makeitbig {
  my $default_value = 'xxx';
  if (@_) {
    $default_value = shift;
  }
  return $default_value;
}
sub testmode {
  my $random1 = int( rand(makeitbig()) );
  return $random1;    
}
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BTW, this could be rewritten:

# not tested, but you get the gist
sub makeitbig {
  return @_ ? shift @_ : 'xxx';
}
sub testmode {
  return int( rand(makeitbig()) );    
}
[download]