Java Program to find out the sum of first n natural numbers

Here we are explaining how to write a java program to find out the sum of first n natural numbers. So first we have to read the value of n from the user. Then by using a while loop we can find out the sum of 1 to n numbers.

What is the syntax of the while loop?

The syntax of the while loop is shown below.


while(condition)
{
   statements;
}

In while loop,the statements are executed repeatedly when it satisfy the condition.

How to implement the java program to display the sum of first n natural numbers?

First, we have to declare the class sumOfNatural .Then declare the variables n,i,sum as an integer.set i=1 and sum=0.Create an object of the Scanner class as s. Read the limit of the number into the variable n.By using a while loop check i<=n,then calculate sum=sum+i.Increment i by one. Then display the sum of first n natural numbers as a sum.

 

ALGORITHM

STEP 1: Declare the class SumOfNatural with a public modifier.

STEP 2: Open the main() to start the program, Java program execution starts with the main()

STEP 3: Declare the integer variables n,i,sum.Set sum=0.

STEP 4: Read the limit of the number into the variable n.

STEP 5: By using a while loop check i<=n do step 6.

STEP 6: Calculate sum=sum+i.

STEP 7: Increment i by one and do step 5.

STEP 8: Display sum.

Java Source Code

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

OUTPUT

Enter the limit of the number :4
Sum of 4 numbers is :10