Java Program to Display Sum of Series 1/2 + 1/3 + 1/4 + 1/5 + … + 1/N

In the previous article we have discussed about Java Program to Print Series 0 7 26 63 …N

In this article we are going to see how to find sum of the series 1/2 + 1/3 + 1/4 + 1/5 + … + 1/N by using Java programming language.

Java Program to Display Sum of Series 1/2 + 1/3 + 1/4 + 1/5 + … + 1/N

On observing the pattern carefully, we can see

Numerator is 1 (fixed)

In Denominator, the number starts from 2 and the next number is 1 added with the previous denominator number.

‘n’ is the no of nth term in the series.

Example:

Suppose value of n = 3
Then the sum of series is 
1/2 + 1/3 + 1/4  
= 0.5 + 0.34 + 0.25 
= 1.09

Let’s see different ways to find sum of the series 1/2 + 1/3 + 1/4 + 1/5 + … + 1/N.

By Using Static Input Value
By Using User Input Value
By Using User Defined Method

Method-1: Java Program to Display Sum of Series 1/2 + 1/3 + 1/4 + 1/5 + … + 1/N By Using For Loop

Approach:

Create Scanner class object.
Declare an integer variable say ‘n’ which holds the value of number of terms of the series.
Prompt the user to enter a number as value of n.
Declare an double variable say ‘sum’ and assign the value to 0.
Use a for loop from i=2 to i<=n+1 and incremented by 1
Inside loop we will find the value of 1 / i, and then we will add that value in sum for each iteration.
Print the result.

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 number of term ");
        int n = s.nextInt();
        //for loop to print the series
        double sum = 0;
        for (int i = 2; i <= n+1; i++) 
        {
            double result =(double) 1 / i;
            sum += result;
        }
        System.out.println("Sum of the series is " +sum);
    }
}

Output:

Enter the number of term 
3
Sum of the series is 1.0833333333333333

Method-2: Java Program to Display Sum of Series 1/2 + 1/3 + 1/4 + 1/5 + … + 1/N By Using While Loop

Approach:

Create Scanner class object.
Declare an integer variable say ‘n’ which holds the value of number of terms of the series.
Prompt the user to enter a number as value of n.
Declare an double variable say ‘sum’ and assign the value to 0.
Declare and initialize an integer variable i=2
Continue a while loop from i=2 to i<=n+1 and incremented by 1.
Inside loop we will find the value of 1 / i, and then we will add that value in sum for each iteration.
Print the result.

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 number of term  ");
        int n = s.nextInt();
        //while loop to print the series
        double sum = 0;
        int i = 2;
        while (i <= n+1) 
        {
            double result =(double) 1 / i;
            sum += result;
            i ++;
        }
        System.out.println("sum of the series is " + sum);
    }
}

Output:

Enter the number of term 
3
sum of the series is 1.0833333333333333

Method-3: Java Program to Display Sum of Series 1/2 + 1/3 + 1/4 + 1/5 + … + 1/N By Using User Defined Method

Approach:

Create Scanner class object.
Declare an integer variable say ‘n’ which holds the value of number of terms of the series.
Prompt the user to enter a number as value of n.
Then call a user defined method printSeries() and pass n as parameter.
Inside method declare an double variable say ‘sum’ and assign the value to 0.
Use a for loop from i=2 to i<=n+1 and incremented by 1
Inside loop we will find the value of 1 / i, and then we will add that value in sum for each iteration.
Print the result.

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 number of term  ");
        int n = s.nextInt();
       // calling m1 method to print the series
        printSeries(n);
   }
    //user defined method printSeries() to print the series
    public static void printSeries(int n)
    {
       //for loop to print the series
        double sum = 0;
        for (int i = 2; i <= n+1; i++) 
        {
            double result =(double) 1 / i;
            sum += result;
        }
        System.out.println("Sum of the series is " +sum);
    }
}

Output:

Enter the number of term 
7
Sum of the series is 1.7178571428571427

Guys who are serious about learning the concepts of the java programming language should practice this list of programs in java and get a good grip on it for better results in exams or interviews.

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