Loading Text then Covert to Number. Really Need help guys.

I loading text from text file, but how to covert the string to number.

[Last_Minder]

First of all. thanks for helping me out.
So my question is:
I'm using a button to ctrl the items that loading into the text file(txt_F),then after load the last item,the "Next Button(B_dis) will disable,and there are 3 items in the text file so far,it will be more later on, so I give a parameter "a" set to 3 first to ctrl how many items will be, but on line number 4, it's never return any "Number Value" but strings. So How can I convert the text to number.Thanks again!
code
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1. txt = new LoadVars();
2. txt.onLoad = function() {
3. _root.txt_F.text = this["c"+i];
 
4. if (checker == Number(this["c"+i]) ){ 
5. _root.B_dis.enabled = false;
6. _root.B_dis._alpha = 60;}
7. };
8. txt.load("text.txt");

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text.txt file include:
-------------------
&a=3
&c1=city
&c2=location
&c3=post code
-------------------

[BlobFisk]

Welcome to WebmasterWorld, Last_Minder!

Where in your code are you loading in the value of "a"?

As well as Number(String) there is also parseInt(String) and parseFloat()...