#! perl -slw
use strict;
use Math::BigInt;
use Time::HiRes qw[ time ];
use feature qw(say);

my $start = time;

my $bn = Math::BigInt->bfac( 1000 );
my %result;
$result{ 1000 } = $bn->bstr;

for( 1001..2000 ) {
    $bn *= $_;
    $result{ $_ } = $bn->bstr;
}

my $end = time;
printf "Took %.6f seconds\n", $end - $start;