# 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:

 2 1 1/2 1/4 1/8 1/16 …… N

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

### 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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