Miscellaneous

Special variables

Rounding

use strict;
use warnings;
use Math::Round; #http://search.cpan.org/~grommel/Math-Round-0.06/Round.pm

my $f = 3.1415926535;
my $r = printf("%.3f", 3.1415926535);

print "$r\n";

use strict;
use warnings;
use feature 'say';

use POSIX qw (floor ceil);

my $float = 1.234;

say floor($float);
say ceil($float);

# https://metacpan.org/pod/distribution/perl/ext/POSIX/lib/POSIX.pod

Use English

http://perldoc.perl.org/English.html

use English;

Block comments

See http://learn.perl.org/faq/perlfaq7.html#How-can-I-comment-out-a-large-block-of-Perl-code