#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper::Simple;
use List::Util qw/shuffle/;

my @nums = (4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20);
my @shuffled_nums = shuffle(@nums);
my %extracted_nums;

for (0 .. 7) {
    $extracted_nums{$_} = shift @shuffled_nums;
}

print Dumper(%extracted_nums);
print Dumper(@shuffled_nums);