#! perl -slw
use strict;

my %cache;

$cache{ sprintf( "%0.8x", rand() * rand() * 0xffffffff ) } = undef for 1 .. 1_000_000;

printf "1 million attempts produced %d keys\n", scalar keys %cache;
printf "between %s and %s\n", (sort keys %cache)[ 0, -1 ];
__END__
P:\test>junk
1 million attempts produced 994758 keys
between 00000000 and ffae0137