Java Program to Print the Series 1+ 2 + 3 + 4 + … + N

In the previous article we have discussed about Java Program to Find the Sum of Series 1!/1 + 2!/2 + 3!/3 + 4!/4+ 5!/5 + N!/N

In this article we are going to see how to print the series 1+ 2 + 3 + 4 + … + N by using Java programming language.

Java Program to Print the Series 1+ 2 + 3 + 4 + … + N

On observing the pattern carefully, we can see

First, number starts from 1, then the next term is incremented by 1 with the previous term.

And finally all the terms are added.

Example:

n = 5

1+2+3+4+5 = 15

Alternative, we can directly use the formula as (n*(n+1))/2

n = 5

(n*(n+1))/2 = 5*6/2 = 15

……

+1 +1 +1 +1 +1

Let’s see different ways to

By Using For Loop
By Using While Loop
By Using User Defined Method

Method-1: Java Program to Print the Series 1+ 2 + 3 + 4 + … + N By Using For Loop

Approach:

Create Scanner class object.
Declare an integer variable say ‘n’ which holds the number of terms in series.
Prompt the user to enter a number as value of n.
Let declare an integer variable say ‘sum’ and initialize it to 0.
Use a for loop from i=1 to i<=n where the loop is incremented by 1.
Inside the for loop we will find the value of sum=sum+i
Print the result in the series.

Program:

import java.util.*;
public class Main
{
    public static void main(String [] args)
    {
        //creating object of Scanner class 
        Scanner s = new Scanner(System.in);
        //Taking input of number of elements in the series
        System.out.println("Enter the Nth term “N” ");
        int n = s.nextInt();
        int sum = 0;
        //for loop to print the series
        for (int i = 1; i <= n; i++) 
        {
            sum+=i; 
        } 
        System.out.print("The sum of the series is "+sum);
    }
}

Output:

Enter the Nth term “N” 
5
The sum of the series is 15

Method-2: Java Program to Print the Series 1+ 2 + 3 + 4 + … + N By Using While Loop

Approach:

Create Scanner class object.
Declare an integer variable say ‘n’ which holds the Nth term of the series.
Prompt the user to enter a number as value of n.
Let declare integer variable say ‘sum’ and initialize it to 0
Declare and initialize an integer variable i=1
Continue a while loop till i<=n, where i is incremented by 1.
Inside while loop find the value of sum+=i
Print the result in the series.

Program:

import java.util.*;
public class Main
{
    public static void main(String [] args)
    {
        //creating object of Scanner class 
        Scanner s = new Scanner(System.in);
        //Taking input of number of elements in the series
        System.out.println("Enter the Nth term “N” ");
        int n = s.nextInt();
        int sum = 0;
        int i=1;
        while(i<=n)
        {
            sum +=i; 
            i++;
        } 
  	    System.out.print("The sum of the series is  "+sum);
    }
}

Output:

Enter the Nth term “N” 
7
The sum of the series is 28

Method-3: Java Program to Print the Series 1+ 2 + 3 + 4 + … + N By Using User Defined Method

Approach:

The same logic as method 1 but this time we are moving the for inside a user-defined method.
Create a Scanner class object.
Prompt the user to enter a value for n which is the number of terms in series.
Call a user defined method printSeries() by passing n as parameter.
Inside the method we will use direct formula as n*(n+1)/2 to find the sum series.
Print the result in the series.

Program:

import java.util.*;
public class Main
{
    public static void main(String[] args)
    {
        // creating object of scanner class 
        Scanner s = new Scanner(System.in);
        //Taking input of number of elements in the series
        System.out.println("Enter the value of Nth term 'N' ");
        int n = s.nextInt();
        // calling printSeries method to print the series
        printSeries(n);
    }
    
    //printSeries metthod to print the series
    public static void printSeries(int n)
    {
        int result = n*(n+1)/2;
        System.out.print("The sum of the series is "+result);
    }
}

Output:

Enter the value of Nth term 'N' 
9
The sum of the series is 45

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