# 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 2 3 4 5 6 …… N

+1                   +1                     +1                   +1                  +1

Let’s see different ways to

### 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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