Java Program to Calculate the Sum of Natural Numbers

by

The best and excellent way to learn a java programming language is by practicing Simple Java Program Examples as it includes basic to advanced levels of concepts.

Program to Calculate the Sum of Natural Numbers

Natural numbers are the numbers 1, 2, 3, 4… which are also called counting numbers. These are basically whole numbers except 0.

We can find the sum of natural numbers in Java using the following methods-

Method-1 : Sum of natural numbers using while loop

We will be taking the last element as input from the user and run the while loop while our counter is less than the number.

Let’s see the below program to understand it more clearly.

import java.util.Scanner;
class sumNatural
{
    public static void main(String args[])
    {
        System.out.println("Enter the last element");
        //Taking input from user
        Scanner scan = new Scanner(System.in);
        int num = scan.nextInt();
        int i=0, sum=0;
        while(i<=num)
        {
            //Iterating the counter for each iteration
            //and adding the value to the previously existing sum. 
            sum+=i;
            i++;
        }
        System.out.println("The sum of natural numbers including "+num+" is "+sum);
    }
}

Output:

Enter the last element
50
The sum of natural numbers including 50 is 1275

Method-2 : Sum of natural numbers using for loop

Like the previous example we will be taking the last element as input from the user and run the for loop but, here we won’t have to use another iterator. The for loop iterator will do the work.

Let’s see the below program to understand it more clearly.

import java.util.Scanner;
class sumNatural
{
    public static void main(String args[])
    {
        System.out.println("Enter the last element");
        //Taking input from user
        Scanner scan = new Scanner(System.in);
        int num = scan.nextInt();
        int sum=0;
        for(int i=1;i<=num;i++)
        {
            //adding the iterator valueto the prevously existing sum. 
            sum+=i;
        }
        System.out.println("The sum of natural numbers including "+num+" is "+sum);
    }
}

Output:

Enter the last element
50
The sum of natural numbers including 50 is 1275

Method-3 : Sum of natural numbers using formula

We can also find the sum of natural numbers using the math formula.

            Sum = n(n+1)/2;

Let’s see the below program to understand it more clearly.

import java.util.Scanner;
class sumNatural{
    public static void main(String args[])
    {
        System.out.println("Enter the last element");
        //Taking input from user
        Scanner scan = new Scanner(System.in);
        int num = scan.nextInt();
        //Using the math formula to calculate the sum
        int sum=num*(num+1)/2;
        System.out.println("The sum of natural numbers including "+num+" is "+sum);
    }
}

Output:

Enter the last element
50
The sum of natural numbers including 50 is 1275

Method-4 : Sum of natural numbers using recursion

 We can find the sum of natural numbers using recursion inside an user defined function.

import java.util.Scanner;
class sumNatural
{
    public static int sumNumbers(int num) 
    {
        //Recursive function
        if (num != 0)
            return num + sumNumbers(num - 1);
        else
            return num;
    }
    public static void main(String args[])
    {
        System.out.println("Enter the last element");
        //Taking input from user
        Scanner scan = new Scanner(System.in);
        int num = scan.nextInt();
        //Using recursive function to calculate the sum
        System.out.println("The sum of natural numbers including "+num+" is "+sumNumbers(num));
    }
}

Output:

Enter the last element
50
The sum of natural numbers including 50 is 1275

Method-5 : Sum of natural numbers between a range using an user defined function(do-while loop)

We can find the sum of a particular range using a do-while loop inside a user-defined function. We have to set the counter to the lower limit of the range.

import java.util.Scanner;
class sumNatural
{
    public static int sumNumbers(int lowerRange, int upperRange) 
   {
    int sum = 0;    
        do{
            sum+=lowerRange++;
        }while(lowerRange!=upperRange);
        return sum;
    }
    public static void main(String args[])
    {
        int lowerRange = 10, upperRange = 90;
        System.out.println("The sum of natural numbers from "+lowerRange+" and "+upperRange+" is "+sumNumbers(lowerRange,upperRange));
    }
}

Output:

The sum of natural numbers from 10 and 90 is 3960

Get started with learning the programming language Java from beginner to experienced level by referring to our collection of Java Programs with Source Code and become a pro in the subject.

Related Java Decision Making and Loop Programs: