compute 10k'th digit of sqrt(2) in Perl 6

sqrt.p6

my Int $i = 2 * 10 ** 20_002;
my Int $sqrt = 10 ** 10_001;
my Int $next_sqrt = ($i div $sqrt + $sqrt) div 2;

loop {
    $sqrt = $next_sqrt;
    $next_sqrt = ($i div $sqrt + $sqrt) div 2;
    last if $sqrt == $next_sqrt;
}

say $sqrt.Str.substr(*-2, 1);