my feedback for this lab was to elminate variables used only once. can someone explain that to me and how it should look?

import java.util.Scanner;

public class Circles$03\{$

public static void main$($String$[]$ args$)\{$

$//$ Method for radius calculation.

double radius $=$ getRadius$()$;

$//$ Method for circumference calculation.

calculateCircumference$($radius$)$;

$//$ Method for area calculation.

calculateArea$($radius$)$;

$//$ Method for rounded area calculation.

calculateRoundedArea$($radius$)$;

$\}$

$/*$ This method gets the radius from the user and returns the

$*$ user$-$input radius.

$*/$

public static double getRadius$()\{$

$//$ Instantiates the scanner.

Scanner in $=$ new Scanner$($System$.$in$)$;

$//$ Prompts the user for a radius and stores as a return double.

System.out.println$("$Radius:$")$;

return in$.$nextDouble$()$;

$\}$

$/*$ This method calculates and displays the circumference of the

$*$ circle. The parameter is the radius of the circle.

$*/$

public static void calculateCircumference$($double radius$)\{$

$//$ Calculates and outputs the circumference of the circle.

double circumference $=(2*$ Math.PI $*$ radius$)$;

System.out.println$("$CIRCUMFERENCE $="+$ circumference$)$;

$\}$

$/*$ This method calculates and displays the area of the circle.

$*$ The parameter is the radius of the circle.

$*/$

public static void calculateArea$($double radius$)\{$

$//$ Calculates and outputs the area of the circle.

double area $=$ Math.PI $*$ Math.pow$($radius$,2)$;

System.out.println$("$AREA $="+$ area$)$;

$\}$

$/*$ This method calculates and displays the rounded area of the

$*$ circle. The parameter is the radius of the circle.

$*/$

public static void calculateRoundedArea$($double radius$)\{$

$//$ Calculates the rounded area of a circle.

double area $=$ Math.PI $*$ Math.pow$($radius$,2)$;

$//$ Creates a variable for the rounded area and casts it

$//$ to an integer.

int roundedArea $=($int$)$ Math.round$($area$)$;

$//$ Outputs the rounded area.

System.out.println$("$ROUNDED AREA $="+$ roundedArea$)$;

$\}$

$\}$