Here is a basic example of how to subtract two numbers (integers) in Perl.

my $sum = (2 - 1);
print "$sum \n";

Which should return the following.

1

Decrement

-- can be used to decrement a value by one.

my $value = 10;
--$value;
print "$value \n";

Which should return the following.

9

Decimal numbers

By default, decimal will be used.

my $sum = (1.8 - 1.1);
print "$sum \n";

Which should return the following.

1.7

Whole numbers

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

use integer;
my $sum = (2.4 - 1.1);
print "$sum \n";

Which should return the following.

1