use strict;
use warnings;
use Math::BigFloat;

my $n = Math::BigFloat->new(7);
my $k = 5;
print $n->bnok($k), "\n"; # prints "21".

my $n2 = 7;
print $n2->bnok($k); # line 10

##</code><code>##

21
Can't call method "bnok" without a package or object reference at bnok.pl line 10.