hex root decimals in raku

get root decimals in hex.raku

sub integer_root ( Int $p where * >= 2, Int $n --> Int ) {
    my Int $d = $p - 1;
    my $guess = 10**($n.chars div $p);
    my $iterator = { ( $d * $^x   +   $n div ($^x ** $d) ) div $p };
    my $endpoint = {      $^x      ** $p <= $n
                     and ($^x + 1) ** $p >  $n };
    min (+$guess, $iterator ... $endpoint)[*-1, *-2];
}

say (($_ - .Int)*2**64).fmt("%0x") given integer_root( 2, 2 * 2**128 ).FatRat / 2**64;