calculus-logic-update-calculation-result.dart

class _CalculusScreenState extends State<CalculusScreen> {
  ...
    
  void onCalulatorResultChanged(num value) {
    setState(() {
      calculatorValue = value;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      ...
      // memory and upate callback added
      CalculatorInput(memory: memory, onChanged: onCalulatorResultChanged),
    );
  }
}