Question

This is an exercise using a while loop Input an integer n from the keyboard. Calculate the sum of the first n integers. So if n=10, the answer should be 55 (because 1+2+3+4+5+6+7+8+9+10=55)

Code language: Java

Answer 1

Java program to find the sum of first n numbers using while loop:
Step-1: Declare and initialize the required variables- n, sum=0, i=1.
Step-2: Ask the user to enter a integer number and store it in the variable n.
Step-3: Use the while loop to check if i (i.e. 1) is less than or equal to n,
3.1: If true, then add the value of i to sum, and increment the value of i by 1, then again check the condition i<=n, if true repeat the step-3.1.
3.2: Once it becomes false, then come out of the while loop and execute the next statement following the while loop i.e. the print the sum statement.

The complete program is shown below:

import java.util.Scanner;
public class Main
{
   public static void main(String[] args)
   {
   int n, i=1, sum=0;
       System.out.print("Enter the integer: ");
       Scanner scan=new Scanner(System.in);
       n= scan.nextInt();
       while(i<=n)
       {
       sum=sum+i;
       i++;
       }
       System.out.println("Sum of the first " + n + " numbers is: " +sum);
   }
}

The screenshot of the complete program along with the output and explanation is shown below:

Output-1:

Output-2: