Help with flash calculator...

[lisafrench]

I have been working on a flash calculator and after many hours of research and much help from other people I have learned enough to write a simple calculator...however, I wanted to add comma's to the input box, and this is where I am having the trouble. It would be easier to just show you what I mean so please look here: http://www.memoryvilleusafoundation....lculate11.html

You will notice that when inputing a number to the thousands (i.e. 2000) it automatically puts the comma in the proper place, however if you put in something any higher there are serious problems in both the input box and the copycat box. Here is the code I have now:

btn_mc.onPress=function(){
total_txt.text = "$"+addCommas(Number(killCommas(num1_txt.text)*5)) +".00";
total2_txt.text = "$"+addCommas(Number(killCommas(num1_txt.text)*25) )+".00";
total3_txt.text= "$"+addCommas((Number(killCommas(num1_txt.text)*25 ))+(Number(killCommas(num1_txt.text)*5)))+".00";
}
function addCommas(theNumber){
numString = theNumber + ""; //convert # to string
newString = ""; //return string
index = 1; // string index
trip = 0; // trip, as in triple.
while( numString.length >= index){
if (trip!=3){ //haven't reached 3 chars yet
newString = numString.charAt(numString.length - index) + newString; //add char
index++;
trip++;
}
else{ //reached 3 chars, add comma
newString = "," + newString;
trip=0;
}
}
return (newString);
}
trace(Number("5,000") + 5);
//traces "NaN"
killCommas = function(s:String):String {
return s.split(",").join("");
}
trace(killCommas("5,000") + 5);
//traces "50005"
trace(Number(killCommas("5,000")) + 5);
//traces "5005"
num1_txt.onChanged=function(){
num1_txt.text =+addCommas(this.text);
num2_txt.text =(this.text);
}

If someone could help me I would be forever grateful.

Thanks,