function NumberDirectory() {}
NumberDirectory.prototype.write = function(num) {
	var len = (num+'').length;
	var rlen = 9-len;
	var base = '000000000';
	var pad = base.substr(0,rlen) + num;
	var s1 = pad.substr(0,3);
	var s2 = pad.substr(3,3);
	var s3 = pad.substr(6,3);
	return (s1 + '/' + s2 + '/' + s3);
}