Fivenum

sub fourths ( Int $end ) {
    my $end_22 = $end div 2 / 2;

    return 0, $end_22, $end/2, $end - $end_22, $end;
}
sub fivenum ( @nums ) {
    my @x = @nums.sort(+*)
        or die 'Input must have at least one element';

    my @d = fourths(@x.end);

    return ( @x[@d».floor] Z+ @x[@d».ceiling] ) »/» 2;
}

say .&fivenum for [15, 6, 42, 41, 7, 36, 49, 40, 39, 47, 43],
                  [36, 40, 7, 39, 41, 15], [
    0.14082834,  0.09748790,  1.73131507,  0.87636009, -1.95059594,
    0.73438555, -0.03035726,  1.46675970, -0.74621349, -0.72588772,
    0.63905160,  0.61501527, -0.98983780, -1.00447874, -0.62759469,
    0.66206163,  1.04312009, -0.10305385,  0.75775634,  0.32566578,
];

Output:

(6 25.5 40 42.5 49)
(7 15 37.5 40 41)
(-1.95059594 -0.676741205 0.23324706 0.746070945 1.73131507)