function addone () {

	// update the hidden field saying how many participants there are
	var current = $('#participants').val();
	var updated = Number(current) + 1;
	$('#participants').val(updated);

	// add fields for an additional participant to the form, passing along the participant number
	$.ajax({
		type: "POST",
		url: "/js/ajax-add_participant.php",
		data: "number="+updated,
		success: function(msg){
			$("#addone").before(msg);
		}
	});
	
}