Q)When to use for loop and when to use while loop?
    =>There is no hard and fast rule to use a particular loop statement
    to solve a problem that involves repetetion. We can use any one of
    them. But coding convenience has to be taken into consideration.

    =>If the number of iterations if we know in advance, better go for
    for loop. If not, go for while loop.

Q)Java program to display the multiplication table of user's choice
upto 10 multiples.
//MultiplicationTable.java
import java.util.Scanner;
class MultiplicationTable{
  public static void main(String args[]){
	  Scanner scanner=new Scanner(System.in);
	  System.out.print("Which multiplication table to print?");
	  int table=scanner.nextInt();
	  for(int i=1;i<=10;i++) {
               System.out.println(table+"X"+i+"="+(table*i));
      	  }//for
  }//main 
}//class
Q)Java program to find the sum of the digits of a number.
//SumOfDigits.java
import java.util.Scanner;
class SumOfDigits{
  public static void main(String args[]){
	  Scanner scanner=new Scanner(System.in);
	  System.out.print("Enter the number:");
	  int n=scanner.nextInt();//234
	  int sum=0;//to hold the sum of the digits
	  while(n>0){
                   sum=sum+n%10;
		   n=n/10;
	  }
	  System.out.println("The sum of the digits is "+sum);
  }//main 
}//class

                  OR

import java.util.Scanner;
class SumOfDigits{
  public static void main(String args[]){
	  Scanner scanner=new Scanner(System.in);
	  System.out.print("Enter the number:");
	  int n=scanner.nextInt();//234
	  int temp=n;//to maintain another copy of n
	  int sum=0;//to hold the sum of the digits
	  while(n>0){
           sum=sum+n%10;
		   n=n/10;
	  }
	  System.out.println("The sum of the digits of "+temp+" is "+sum);
  }//main 
}//class

Q)Java program to find if a number is a palindrome.
import java.util.Scanner;
class Palindrome{
  public static void main(String args[]){
	  Scanner scanner=new Scanner(System.in);
	  System.out.print("Enter the number:");
	  int n=scanner.nextInt();//234
	  int temp=n;//to maintain another copy of n
	  int reverse=0;//to hold the sum of the digits
	  while(n>0){
                   reverse=reverse*10+n%10;
		   n=n/10;
	  }
	  if(temp==reverse){
	    System.out.println("It is a palindrome");
	  }
	  else{
	     System.out.println("It is not a plaindrome");
	  }
  }//main 
}//class
Q)What is the output of the following program?
import java.util.Scanner;
class NestedLoop{
  public static void main(String args[]){
	  for(int i=1;i<4;i++){
		  for(int j=1;j<=3;j++){
			  System.out.println(i+""+j);
		  }
	  }
  }//main 
}//class

Ans:-
1  1
1 2
1 3
2 1
2 2
2 3
3 1
3 2
3 3

Note:- For each iteration of outer loop, all the iterations of
inner loop will be completed