Making a Timer Countdown

programming flash
1

Following is a script that I’m using for a count-up timer, I would like to convert it to a count-down timer (from 12 minutes). Any suggestions?

//initial variables
var countdown:Number=720000;
var miltonscore:Number=0;
var themscore:Number=0;
var timing:Boolean = false;
var paused:Boolean = false;
var remaining:Number;
var elapsedTime:Number;
var elapsedM:Number;
var elapsedS:Number;
var startTime:Number;
var remaining:Number;
var minutes:String;
var seconds:String;


//////////////////////

_root.play_btn.onPress = function() {
	if(!_root.timing) {
		if (_root.paused) {
			_root.startTime =getTimer()-_root.elapsedTime;
		} else {
			_root.startTime =getTimer();
		}
		//start timer
		_root.paused = false;
		_root.timing = true;
	}
	//pause timer
	else{
		_root.timing = false;
		_root.paused = true;
	}
}

/////////////////////////////////////

_root.onEnterFrame = function() {
	_root.home_text=miltonscore;
	_root.them_text=themscore;
	
	if (timing) {
		//calculate values
		elapsedTime =getTimer()-startTime;
		//hours
		elapsedHours = Math.floor(elapsedTime/3600000);
		remaining = elapsedTime-(elapsedHours*3600000);
		//minutes
		elapsedM = Math.floor(remaining/60000);
		remaining = remaining+(elapsedM*60000);
		//seconds
		elapsedS = Math.floor(remaining/1000);
		remaining = remaining-(elapsedS*1000);
		//hundredths
		elapsedH = Math.floor(remaining/10);
		//output to text box
		//add a 0 on the front of the numbers if the number is less than 10
		if (elapsedHours<10) {
			hours = "0"+elapsedHours.toString();
		} else {
			hours = elapsedHours.toString();
		}
		if (elapsedM<10) {
			minutes = "0"+elapsedM.toString();
		} else {
			minutes = elapsedM.toString();
		}
		if (elapsedS<10) {
			seconds = "0"+elapsedS.toString();
		} else {
			seconds = elapsedS.toString();
		}
		if (elapsedH<10) {
			hundredths = "0"+elapsedH.toString();
		} else {
			hundredths = elapsedH.toString();
		}
		_root.timer_txt = minutes+":"+seconds;
		
		
		
	}
};