It's not recognizing the numberEntered string value I'm passing to it to parse.
And there's your problem: Where are you passing it anything? The method has no parameters (a String parameter would work nicely here), and the variable you're trying to get is local to the main method and thus invisible to the method.
My recommendation: Keep the variable local and use a parameter to pass the String to the method.
I’ve looked at a lot of different solutions, and in my humble opinion Aspose is the way to go. Here’s the link: http://aspose.com