Here is one way. Look at the String class for an explanation as well as other possible methods you might be able to use...
var st:String = "THE MOUSE CAUGHT THE RAT AT POST 324S58";
var st2 = st.slice(-3);
trace(st2); // S58
Thanks for the reply NED.
The sentence is an uncertain (it's a random pick and desplay). What I need is just to extract the final 3.
The sentence will be displayed in a dynamic text box (instance: "quote")
The output text box instance is "result"
will it work like this?
var quote:String = quote.text;
var result = quote.slice(-3);
You'll be asking for trouble using a variable that has the same name as a textfield.
result.text = String(quote.text).slice(-3);