var http = getHTTPObject();
 
function getHTTPObject()  {
	if( window.XMLHttpRequest )
		return new window.XMLHttpRequest;
	else {
		try {
			return new ActiveXObject( "MSXML2.XMLHTTP.3.0" );
		}
		catch( ex ) {
			return null;
		}
	}
}
 
function doMath() {
	var url = "1fix.php?op=" + document.getElementById('op').value;
	url += "&num1=" + document.getElementById('num1').value;
	url += "&num2=" + document.getElementById('num2').value;
 
	http.open("GET", url, true);
	http.onreadystatechange = handleHttpResponse;
 
	http.send(null);
}
 
function handleHttpResponse() {
	if( http.readyState == 4 ) {
		document.getElementById('answer').innerHTML = http.responseText;
	}
}