Calculator::mul PHP Method

    public function mul($a, $b)
    {
        return $a * $b;
    }

    public function div($value)
    {
        return $this->answer /= (double) $value;
    }
    public function clear()
    {
        $this->answer = 0;
    }
    public function eq()
    {
        return $this->answer;
    }
}
// Spl auto loader
require 'SplClassLoader.php';
$loader = new SplClassLoader(null, implode(DIRECTORY_SEPARATOR, array(__DIR__, '..', 'src')));
$loader->register();
// Calculator
$calc = new Calculator();
$calc->add(15);
// answer = 15
$calc->mul(3);
// answer = 45
$calc->div(9);
// answer = 5
echo $calc->eq();
// prints 5
echo "\n";
// Implement calculator chain
$chain = new \Chainnn\Chain($calc, array('add', 'sub', 'mul', 'div', '^clear', '$eq'));
echo $chain->clear()->add(100)->div(5)->sub(10)->mul(3)->eq();