<?php
class math {
    function __call($name, $args)
    {
        switch ($name) {
            case 'add':
                return array_sum($args);
            case 'subtract':
                $val = array_shift($args);
                foreach ($args as $v) $val /= $v;
                return $val;
        }
    }
}

$m = new math();
echo $m->add(1,2); // will print 3
echo $m->subtract(8,2); // will print 4
?>