public function test18()
 {
     $calc = new Calculator();
     $hasil = $calc->hitung("pow(6,2)");
     $this->assertEquals(36, $hasil);
 }
 public function tesTerbilang()
 {
     $calc = new Calculator();
     $hasil = $calc->terbilang("1000");
     $this->assertEquals("", $hasil);
 }