# Program to find the Nth Harmonic Number

• Last Updated : 12 Apr, 2021

Given a number N. The task is to find the Nth Harmonic Number.
Let the nth harmonic number be Hn.
The harmonic series is as follows:

H1 = 1
H2 = H1 + 1/2
H3 = H2 + 1/3
H4 = H3 + 1/4

Hn = Hn-1 + 1/n

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Examples

```Input : N = 5
Output : 2.45

Input : N = 9
Output : 2.71786```

The idea is to traverse from H1 and then consecutively keep finding H2 from H1, H3 from H2 ….. and so on.
Below is the program to find N-th Harmonic Number:

## C++

 `// CPP program to find N-th Harmonic Number` `#include ``using` `namespace` `std;` `// Function to find N-th Harmonic Number``double` `nthHarmonic(``int` `N)``{``    ``// H1 = 1``    ``float` `harmonic = 1.00;` `    ``// loop to apply the forumula``    ``// Hn = H1 + H2 + H3 ... + Hn-1 + Hn-1 + 1/n``    ``for` `(``int` `i = 2; i <= N; i++) {``        ``harmonic += (``float``)1 / i;``    ``}` `    ``return` `harmonic;``}` `// Driver Code``int` `main()``{``    ``int` `N = 8;``    ` `    ``cout<

## Java

 `// Java program to find N-th Harmonic Number` `import` `java.io.*;` `class` `GFG {``    ` `// Function to find N-th Harmonic Number``static` `double` `nthHarmonic(``int` `N)``{``    ``// H1 = 1``    ``float` `harmonic = ``1``;` `    ``// loop to apply the forumula``    ``// Hn = H1 + H2 + H3 ... + Hn-1 + Hn-1 + 1/n``    ``for` `(``int` `i = ``2``; i <= N; i++) {``        ``harmonic += (``float``)``1` `/ i;``    ``}` `    ``return` `harmonic;``}` `// Driver Code` `    ``public` `static` `void` `main (String[] args) {``            ``int` `N = ``8``;``    ` `    ``System.out.print(nthHarmonic(N));``    ` `    ``}``}``// This code is contributed``// by ajit`

## Python 3

 `# Python3 program to find``# N-th Harmonic Number` `# Function to find N-th Harmonic Number``def` `nthHarmonic(N) :` `    ``# H1 = 1``    ``harmonic ``=` `1.00` `    ``# loop to apply the forumula``    ``# Hn = H1 + H2 + H3 ... +``    ``# Hn-1 + Hn-1 + 1/n``    ``for` `i ``in` `range``(``2``, N ``+` `1``) :``        ``harmonic ``+``=` `1` `/` `i` `    ``return` `harmonic``    ` `# Driver code    ``if` `__name__ ``=``=` `"__main__"` `:` `    ``N ``=` `8``    ``print``(``round``(nthHarmonic(N),``5``))` `# This code is contributed by ANKITRAI1`

## C#

 `// C# program to find N-th Harmonic Number``using` `System;` `class` `GFG``{``    ` `// Function to find N-th Harmonic Number``static` `double` `nthHarmonic(``int` `N)``{``    ``// H1 = 1``    ``float` `harmonic = 1;` `    ``// loop to apply the forumula``    ``// Hn = H1 + H2 + H3 ... +``    ``// Hn-1 + Hn-1 + 1/n``    ``for` `(``int` `i = 2; i <= N; i++)``    ``{``        ``harmonic += (``float``)1 / i;``    ``}` `    ``return` `harmonic;``}` `// Driver Code``static` `public` `void` `Main ()``{``    ``int` `N = 8;``    ` `    ``Console.Write(nthHarmonic(N));``}``}` `// This code is contributed``// by Raj`

## PHP

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## Javascript

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Output:
`2.71786`

Time Complexity: O(N)

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