# Find the next fibonacci number

• Difficulty Level : Expert
• Last Updated : 10 Mar, 2021

Given a fibonacci number N, the task is to find the next fibonacci number.
Examples:

Input: N = 5
Output:
8 is the next fibonacci number after 5
Input: N = 3
Output:

Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.  To complete your preparation from learning a language to DS Algo and many more,  please refer Complete Interview Preparation Course.

In case you wish to attend live classes with experts, please refer DSA Live Classes for Working Professionals and Competitive Programming Live for Students.

Approach: The ratio of two adjacent numbers in the Fibonacci series rapidly approaches ((1 + sqrt(5)) / 2). So if N is multiplied by ((1 + sqrt(5)) / 2) and round it, the resultant number will be the next fibonacci number.
Below is the implementation of the above approach:

## C++

 // C++ implementation of the approach#includeusing namespace std; // Function to return the next// fibonacci numberint nextFibonacci(int n){    double a = n * (1 + sqrt(5)) / 2.0;    return round(a);} // Driver codeint main(){    int n = 5;    cout << nextFibonacci(n);} // This code is contributed by mohit kumar 29

## Java

 // Java implementation of the approachclass GFG{         // Function to return the next    // fibonacci number    static long nextFibonacci(int n)    {        double a = n * (1 + Math.sqrt(5)) / 2.0;        return Math.round(a);    }         // Driver code    public static void main (String[] args)    {        int n = 5;        System.out.println(nextFibonacci(n));    }} // This code is contributed by AnkitRai01

## Python3

 # Python3 implementation of the approachfrom math import * # Function to return the next# fibonacci numberdef nextFibonacci(n):    a = n*(1 + sqrt(5))/2.0    return round(a) # Driver coden = 5print(nextFibonacci(n))

## C#

 // C# implementation of the approachusing System; class GFG{         // Function to return the next    // fibonacci number    static long nextFibonacci(int n)    {        double a = n * (1 + Math.Sqrt(5)) / 2.0;        return (long)Math.Round(a);    }         // Driver code    public static void Main(String[] args)    {        int n = 5;        Console.WriteLine(nextFibonacci(n));    }} // This code is contributed by 29AjayKumar

## Javascript


Output:
8

My Personal Notes arrow_drop_up