You're almost there. Here's how to define the object and methods:

package MyModule;

# 'constructor'
sub new {
    # if you call MyModule->new, $_[0] will be 'MyModule'
    my $class = shift;

    # $self can be any reference, but usually a hash
    my $self = {};

    # this is the 'magic' that creates the object
    bless $self, $class;
    return $self;
}

sub half {
    # if you call $m->half(10), $_[0] will be the object
    my ( $self, $number ) = @_;

    # proceed as normal
    return $number / 2;
}

package main;
# now no longer in package, but in script

# instantiate object, call constructor
my $m = MyModule->new;

# yields '5'
print $m->half(10);
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What happened in your case was that you tried to divide the first argument in @_ in your 'half' sub by two. However, if you use 'half' as a method call (i.e. $m->half(10), instead of half(10)), the first argument is the $m object (sometimes called the 'invocant'), not the number 10.

Hence, the return value (being whatever you pulled off $_[0]) is the object, which, when printed out, yields Package=REFTYPE(address), in your case Mymodule=HASH(0xbd5068). Instead, you will want to divide the second argument, which is why, conventionally, people will copy from @_ like so: my ( $self, ... ) = @_;

Hope this helps. Good luck!

P.s. you don't need to use EXPORTER for OO modules, as the methods are attached to the objects (rather than having to be imported into the caller's namespace).