public function testMul()
{
$a = 1234;
$b = '1234123412341234123412341234123412412341234213412421341342342';
$c = '0x1234123412341234123412341234123412412341234213412421341342342';
$math = new BcEngine();
$this->assertEquals(1522756, $math->mul($a, $a));
$this->assertEquals('1523060596888771785469376020510342038779135661438916853827453718463560582690945158853917400742616234688308574558442044964', $math->mul($b, $b));
$this->assertEquals('4040760497619659988396017237570892345412667279675376001385393199805230792128304954488986267360185801341164900937850776470852477066413262703893764', $math->mul($c, $c));
$this->assertEquals(1, $math->mul(1, 1));
}