var Aid = new Object();
Aid.init = function ()
{
	var inpts = document.getElementsByTagName('input');
		Core.addEventListener(inpts[3],'click',Aid.calculate);
		Core.addEventListener(inpts[7],'click',Aid.calculate);
		Core.addEventListener(inpts[11],'click',Aid.calculate);
		Core.addEventListener(inpts[15],'click',Aid.calculate);
}
Aid.calculate = function ()
{
	var box = this.parentNode;
	var operation = box.id;
	var num1 = parseFloat(box.getElementsByTagName('input')[0].value);
	var num2 = parseFloat(box.getElementsByTagName('input')[1].value);
	var ans = box.getElementsByTagName('input')[2];
	var result = 0;
	//alert('calculate has been called.');
	//alert(num1+operation+num2);
	if(operation == "add")
	{
		result = num1 + num2;
		ans.value = result;
		//alert('add has been called.'+ result);
	}
	else if(operation == "sub")
	{
		result = num1 - num2;
		ans.value = result;
		//alert('sub has been called.'+ result);
	}
	else if(operation == "mult")
	{
		result = num1 * num2;
		ans.value = result;
		//alert('mult has been called.'+ result);
	}
	else if(operation =="div")
	{
		result = num1 / num2;
		ans.value = result;
		//alert('div has been called.'+ result);
	}
	else
	{
		alert("error");
	}
}
Core.start(Aid);