1)

import java.util.*;

public class ReverseNumber {
    public static int reverse(int num){
        int n = num;
            int reversedNumber = 0;
            for (int i = 0; i <= num; i++) {
                int r = num % 10;
                num = num / 10;
                reversedNumber = reversedNumber * 10 + r;
                i = 0;
            }
            return reversedNumber;
    }
    public static void main(String[] args) {
            Scanner input = new Scanner(System.in);
            System.out.print("Enter number: ");
            int num = input.nextInt();
            System.out.println("Reversed Number: "+reverse(num));
    }
}

2)

import java.util.*;

public class NumberPalindrome {
    public static void main(String[] args) {
        try {
            Scanner input = new Scanner(System.in);
            System.out.print("Enter number: ");
            int num = input.nextInt();
            int n = num;
            int reversedNumber = 0;
            for (int i = 0; i <= num; i++) {
                int r = num % 10;
                num = num / 10;
                reversedNumber = reversedNumber * 10 + r;
                i = 0;
            }
            if (n == reversedNumber) {
                System.out.print("Number is palindrome!");
            } else {
                System.out.println("Number is not palindrome!");
            }
        } catch (Exception e) {
            System.out.println(e);
        }
    }
}

3)

mport java.io.*;
class ArmstrongNumber{

public static void main(String args[]) throws IOException{
BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Please enter number:");
int num = Integer.parseInt(bf.readLine());
int n = num; //use to check at last time
int check=0,remainder;
while(num > 0){
remainder = num % 10;
check = check + (int)Math.pow(remainder,3);
num = num / 10;
}
if(check == n)
System.out.println(n+" is an Armstrong Number");
else
System.out.println(n+" is not a Armstrong Number");
}
}