Пожалуйста помогите . Как упростить такую программу? (Вопрос внтури)

package lesson02;

import java.util.Scanner;

public class Calculator {

public static void main(String[] args) {
int operation = 0, b, c;

while (operation != 5) {

System.out.println("1=+,2=-,3=*,4=/,5=exit");
Scanner reader = new Scanner(System.in);
System.out.println("Введите числа для вычесления");
operation = reader.nextInt();
double d =0;
if (operation ==1 ) {
b = reader.nextInt();
c = reader.nextInt();
d = (b+c) ;}
else if (operation ==2 ) {
b = reader.nextInt();
c = reader.nextInt();
d = (b-c) ;}
else if (operation ==3 ) {
b = reader.nextInt();
c = reader.nextInt();
d = (b*c) ;}
else if (operation ==4 ) {
b = reader.nextInt();
c = reader.nextInt();
d = (b/c) ;
}
System.out.println("Равно " +d);
}

}
}