use Benchmark ':all';

our $a = 347.3;
our $b = 876.1;
our $c;

cmpthese( 5_000_000, 
    {
        'rand' => sub { rand() },
        add => sub { $c = $a + $b },
        mul => sub { $c = $a * $b },
        div => sub { $c = $a / $b },
        'sqrt' => sub { $c = sqrt($b) },
    }
);