Find Calculate Square Root Of Given Number In Flutter

import 'package:flutter/material.dart';
import 'dart:math';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  double SQUARE_1 = 625;
  double SQUARE_2;
  findSquareRoot() {
    SQUARE_2 = sqrt(SQUARE_1);
    print(SQUARE_2);
  }
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
        home: Scaffold(
          appBar: AppBar(
            backgroundColor: Colors.lightGreen,
            title: Text("Square Root Of Given Number"),
          ),
            body: Center(
                child: Column(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: <Widget>[
                      Container(
                          margin: const EdgeInsets.fromLTRB(20, 10, 20, 10),
                          child: RaisedButton(
                            onPressed: () =>findSquareRoot(),
                            child: Text(' Find Square Root Of Number '),
                            textColor: Colors.white,
                            color: Color(0xFFFFC107),
                            padding: EdgeInsets.fromLTRB(10, 10, 10, 10),
                          )),
                    ]
                )
            )
        )
    );
  }
}