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Program for N-th term of Geometric Progression series

  • Difficulty Level : Easy
  • Last Updated : 25 Feb, 2021

Given first term (a), common ratio (r) and a integer N of the Geometric Progression series, the task is to find Nth term of the series.
Examples : 
 

Input : a = 2 r = 2, N = 4
Output :
The 4th term of the series is : 16

Input : a = 2 r = 3, N = 5
Output :
The 5th term of the series is : 162

Approach: 
 

We know the Geometric Progression series is like = 2, 4, 8, 16, 32 …. … 
In this series 2 is the stating term of the series . 
Common ratio = 4 / 2 = 2 (ratio common in the series). 
so we can write the series as :
t1 = a1 
t2 = a1 * r(2-1) 
t3 = a1 * r(3-1) 
t4 = a1 * r(4-1) 




tN = a1 * r(N-1)

To find the Nth term in the Geometric Progression series we use the simple formula . 
 

TN = a1 * r(N-1)

 

 

C++

// CPP Program to find nth term of 
// geometric progression 
#include <bits/stdc++.h>
 
using namespace std; 

int Nth_of_GP(int a, int r, int N) 
{ 
    // using formula to find 
    // the Nth term 
    // TN = a1 * r(N-1) 
    return( a * (int)(pow(r, N - 1)) ); 
    
} 

// Driver code 
int main() 
{ 
    // starting number 
    int a = 2; 
    
    // Common ratio 
    int r = 3; 
    
    // N th term to be find 
    int N = 5; 
    
    // Display the output 
    cout << "The "<< N <<"th term of the series is : "
        << Nth_of_GP(a, r, N); 

    return 0; 
} 


Java

// java program to find nth term 
// of geometric progression 
import java.io.*; 
import java.lang.*; 

class GFG 
{ 
    public static int Nth_of_GP(int a, 
                                int r, 
                                int N) 
    { 
        // using formula to find the Nth 
        // term TN = a1 * r(N-1) 
        return ( a * (int)(Math.pow(r, N - 1)) ); 
    } 

    // Driver code 
    public static void main(String[] args) 
    { 
        // starting number 
        int a = 2; 
        
        // Common ratio 
        int r = 3; 
        
        // N th term to be find 
        int N = 5; 

        // Display the output 
        System.out.print("The "+ N + "th term of the" + 
                " series is : " + Nth_of_GP(a, r, N)); 
    } 
} 

Python3

# Python3 Program to find nth 
# term of geometric progression 
import math 

def Nth_of_GP(a, r, N): 

    # Using formula to find the Nth 
    # term TN = a1 * r(N-1) 
    return( a * (int)(math.pow(r, N - 1)) ) 
    
# Driver code 
a = 2 # Starting number 
r = 3 # Common ratio 
N = 5 # N th term to be find 
    
print("The", N, "th term of the series is :", 
                            Nth_of_GP(a, r, N)) 


# This code is contributed by Smitha Dinesh Semwal 

C#

// C# program to find nth term 
// of geometric progression 
using System; 

class GFG 
{ 
    
    public static int Nth_of_GP(int a, 
                                int r, 
                                int N) 
    { 
        
        // using formula to find the Nth 
        // term TN = a1 * r(N-1) 
        return ( a * (int)(Math.Pow(r, N - 1)) ); 
    } 

    // Driver code 
    public static void Main() 
    { 
        // starting number 
        int a = 2; 
        
        // Common ratio 
        int r = 3; 
        
        // N th term to be find 
        int N = 5; 

        // Display the output 
        Console.Write("The "+ N + "th term of the" + 
            " series is : " + Nth_of_GP(a, r, N)); 
    } 
} 

// This code is contributed by vt_m 

PHP

<?php 
// PHP Program to find nth term of 
// geometric progression 

function Nth_of_GP($a, $r, $N) 
{ 
    // using formula to find 
    // the Nth term TN = a1 * r(N-1) 
    return( $a * (int)(pow($r, $N - 1)) ); 
    
} 

// Driver code 

// starting number 
$a = 2; 

// Common ratio 
$r = 3; 

// N th term to be find 
$N = 5; 
    
// Display the output 
echo("The " . $N . "th term of the series is : "
                    . Nth_of_GP($a, $r, $N)); 

// This code is contributed by Ajit. 
?> 

Javascript

<script>

// JavaScript Program to find nth term of  
// geometric progression  
  
function Nth_of_GP(a, r, N)  
{  
    // using formula to find  
    // the Nth term  
    // TN = a1 * r(N-1)  
    return( a * Math.floor(Math.pow(r, N - 1)) );  
      
}  
  
// Driver code  
 
    // starting number  
    let a = 2;  
      
    // Common ratio  
    let r = 3;  
      
    // N th term to be find  
    let N = 5;  
      
    // Display the output  
    document.write("The "+ N +"th term of the series is : "
        + Nth_of_GP(a, r, N));  
  
 
// This code is contributed by Surbhi Tyagi

</script>

Output : 
 

The 5th term of the series is : 162

 

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