DART: How do I generate a random six (6) digit number in flutter on a button click to display on the next page?

You can use the Random class

          Container(
              width: MediaQuery.of(context).size.width * 3.5/4,
              height: MediaQuery.of(context).size.height * 0.35/4,
              child: RaisedButton(
                color: Colors.indigoAccent,
                textColor: cc.WHITE,
                shape: RoundedRectangleBorder(
                  borderRadius: BorderRadius.circular(10.0),
                ),
                onPressed: () {
                int min = 100000; //min and max values act as your 6 digit range
                int max = 999999;
                var randomizer = new Random(); 
                var rNum = min + randomizer.nextInt(max - min);
                  push(context, Invite(randomNum: rNum)); //pass your random number through
                },
                child: new Text(
                  'GENERATE CODE',
                  style: new TextStyle(
                    fontSize: 14.0,
                    fontWeight: FontWeight.w700,
                    color: Colors.white,
                  ),
                ),
                //text: 'GENERATE CODE',
              ),
            ),

In your class

class Invite extends StatefulWidget{
  Invite(Key key, this.randomNumber):super(key:key);
  final int randomNumber;

  ....//your code

  //to retrieve the number that has been sent use widget.randomNumber
}