Form Field Text Addition

Hello all,

Ok I am fairly new to ASP.NET / C#. 

I have a form that has several TextBoxes that people will put dollar amounts in, ideally I would like the amounts to add up in a another TextBox dynamically.  So lets say I had 4 TextBoxes set-up asking for 4 different amounts... I also had a 5th TextBox for the total.  Joe Blow comes along and fills in the amounts of say 5, 10, 4, & 15.  As he does that it automatically adds it to the the 5th textbox which ends up with a total of 24.

Make sense? Any idea how I could accomplish this?

Thanks in advance!
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