In the State class, let's add a member called _numberFrom. As shown in the following code, this is a value that will change based on user input:
double _numberFrom;
Then, in the body of the build() method, let's delete the text widget, and add TextField instead:
body: Center( child: TextField(),),
You generally use TextField when you want to take some input from your users.
As you can see, there's now TextField in the center of your app, and you can write into it by clicking over the line and typing something:
Right now, TextField does nothing, so the first thing we need to do is read the value that the user ...
