// LuckyController.php

class LuckyController extends Controller
{
    public function numberAction($max)
    {
        $number = mt_rand(0,$max);

        return $this->render('number.html.twig',
        array('number' => $number));
    }
}

// routing.yml
Lucky:
    path: /rndnumber/{max}
    defaults: {
        _controller: AppBundle:Lucky:number, max: 100 }