function calculateForm() {
	var orderCount = document.getElementById('orderCount').value;
	var singlePrice = 42.50;
	var totalAmount = orderCount*singlePrice;
	document.getElementById('orderSum').innerHTML = totalAmount.toFixed(2) + " SFr.";
	
	var fields = ['titlePresent', 'businessPresent'];
	var mandatoryFields = ['namePresent', 'prenamePresent', 'streetPresent', 'plzPresent', 'cityPresent'];

	if (document.getElementById('present').checked == false) {
		for(var i = 0; i < mandatoryFields.length; i++) {
			document.getElementById('hiddenValues').innerHTML += '<input type="hidden" name="mailformplusplus[' + mandatoryFields[i] + ']" value="keine" />';
			var field = document.getElementById(mandatoryFields[i]);
			field.name = mandatoryFields[i] + 'Org';
			field.value = "";
			field.disabled = true;
		}
		for(var i = 0; i < fields.length; i++) {
			document.getElementById(fields[i]).disabled = true;
		}
	} else {
		document.getElementById('hiddenValues').innerHTML = "";
		for(var i = 0; i < mandatoryFields.length; i++) {
			var field = document.getElementById(mandatoryFields[i]);
			field.disabled = false;
			field.name = 'mailformplusplus[' + mandatoryFields[i] + ']';
		}
		for(var i = 0; i < fields.length; i++) {
			var field = document.getElementById(fields[i]);
			field.disabled = false;
		}
	}
}