package{
import flash.display.Sprite;
public class Main extends Sprite{
public function Main(){
var n:Number;
trace(n); //NaN
trace(isNaN(n)); //true
trace(n == NaN); //false! That's why you use isNaN()
n = Number("this won't convert into a number");
trace(isNaN(n)); //true
n = 10;
trace(isNaN(n)); //false
}
}
}