Java Program to Print the Series 2 1 1/2 1/4 1/8 …N

In the previous article we have discussed about Java Program to Print the Series 2 3 12 37 86 166 … N

In this article we are going to see how to print the series 6 11 21 36 56 …N by using Java programming language.

Java Program to Print the Series 2 1 1/2 1/4 1/8 …N

On observing the pattern carefully, we can see first number starts from 2

Then the next number follows a logic i.e previous element/2

2
2/2 = 1
1/2
1/2 / 2 = 1/4
1/4 / 2 = 1/8 and so on.

Example:

1/2

1/4

1/8

1/16

……

Let’s see different ways to print the series 6 11 21 36 56 …N

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

Method-1: Java Program to Print the Series 2 1 1/2 1/4 1/8 …N By Using For Loop

Approach:

Create Scanner class object.
Declare an integer variable say ‘n’ which holds the number of terms in the series.
Prompt the user to enter a number as value of n.
Let declare an double variable say ‘result’ and initialize it to 2
Use a for loop from i=1 to i<=n-1 where the loop is incremented by 1
Inside the for loop we will find the value of result=result/2
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 number of terms ");
        int n = s.nextInt();
        double result = 2;
        System.out.print(result);
        //for loop to print the series
        for (int i = 1; i <= n-1; i++) 
        {
            result /=2; 
            System.out.print(" "+result);
        } 
    }
}

Output:

Enter the number of terms
5
2.0 1.0 0.5 0.25 0.125

Method-2: Java Program to Print the Series 2 1 1/2 1/4 1/8 …N By Using While Loop

Approach:

Create Scanner class object.
Declare an integer variable say ‘n’ which holds the number of terms in the series.
Prompt the user to enter a number as value of n.
Let declare an double variable say ‘result’ and initialize it to 2
Declare and initialize an integer variable i=1
Continue a while loop till i<=n-1, where i is incremented by 1.
Inside the while loop we will find the value of result=result/2
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 number of terms ");
        int n = s.nextInt();
        double result=2;
        System.out.print(result);
        int i=1;
        while(i<=n-1)
        {
            result /=2; 
            System.out.print("  "+result);
            i++;
        }      
    }
}

Output:

Enter the number of terms
7
2.0 1.0 0.5 0.25 0.125 0.0625 0.03125

Method-3: Java Program to Print the Series 2 1 1/2 1/4 1/8 …N By Using User Defined Method

Approach:

Create Scanner class object.
Declare an integer variable say ‘n’ which holds the number of terms in the series.
Prompt the user to enter a number as value of n.
Then call a user defined method printSeries() by passing n as parameter.
Inside method declare an double variable say ‘result’ and initialize it to 2
Use a for loop from i=1 to i<=n-1 where the loop is incremented by 1
Inside the for loop we will find the value of result=result/2
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 number of terms ");
        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)
    {
        double result = 2;
        System.out.print(result);
        //for loop to print the series
        for (int i = 1; i <=n-1; i++) 
        {
            result /=2; 
            System.out.print(" "+result);
        } 
    }
}

Output:

Enter the number of terms
9
2.0 1.0 0.5 0.25 0.125 0.0625 0.03125 0.015625 0.0078125

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