Android : Random Number showing pointnumber and "0"

in this app a random number between 0-5 appears when the button is clicked. The Problem is, that the number appears as a pointnumber instead of a "normal" number. For example: 4.7920870175158825

The second Problem is, that sometimes a number with a 0 before the comma appears, For example: 0.7518324225208361

How can I fix this?

Thank´s in advance. :)

MainActivity.java:

public class MainActivity extends ActionBarActivity {

    Button btn;
    TextView tw;



    @Override
    protected void onCreate(Bundle savedInstanceState) {


        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btn = (Button) findViewById(R.id.btn);
        tw = (TextView) findViewById(R.id.tw);



        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                tw.setText("Random Number: " + Math.random()*5);




            }
        });
    }
}