Here is the most basic example of how to add two numbers in Perl.

#!/usr/bin/perl
use strict;
use warnings;

print (1 + 1);

It is much more common to store the result in a variable.

#!/usr/bin/perl
use strict;
use warnings;

my $sum = (1 + 1);
print "$sum \n";

Which should return the following.

2

Increment

++ can be used to increment a value by one.

my $value = 1;
++$value;
print "$value \n";

Which should return the following.

2

Appending

+= can be used to add to an already set value.

$i = 1;
$i += 2;

print "$i \n";

Which should return the following.

3

Decimal numbers

By default, decimal will be used.

my $sum = (1.1 + 1.1);
print "$sum \n";

Which should return the following.

2.2

Whole numbers

The integer module can be used to round to whole numbers.

#!/usr/bin/perl
use strict;
use warnings;
use integer;

my $sum = (1.1 + 1.1);
print "$sum \n";

Which should return the following.

2