# Find the next fibonacci number

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

**Examples:**

Input:N = 5

Output:8

8 is the next fibonacci number after 5

Input:N = 3

Output:5

**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 ` `#include<bits/stdc++.h> ` `using` `namespace` `std; ` ` ` `// Function to return the next ` `// fibonacci number ` `int` `nextFibonacci(` `int` `n) ` `{ ` ` ` `double` `a = n * (1 + ` `sqrt` `(5)) / 2.0; ` ` ` `return` `round(a); ` `} ` ` ` `// Driver code ` `int` `main() ` `{ ` ` ` `int` `n = 5; ` ` ` `cout << nextFibonacci(n); ` `} ` ` ` `// This code is contributed by mohit kumar 29 ` |

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## Java

`// Java implementation of the approach ` `class` `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 ` |

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## Python3

`# Python3 implementation of the approach ` `from` `math ` `import` `*` ` ` `# Function to return the next ` `# fibonacci number ` `def` `nextFibonacci(n): ` ` ` `a ` `=` `n` `*` `(` `1` `+` `sqrt(` `5` `))` `/` `2.0` ` ` `return` `round` `(a) ` ` ` `# Driver code ` `n ` `=` `5` `print` `(nextFibonacci(n)) ` |

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## C#

`// C# implementation of the approach ` `using` `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 ` |

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**Output:**

8

## Recommended Posts:

- Find the previous fibonacci number
- Program to find Nth odd Fibonacci Number
- Program to find last two digits of Nth Fibonacci number
- Find nth Fibonacci number using Golden ratio
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- Find the longest Fibonacci-like subarray of the given array

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