Given a number ‘n’, how to check if n is a Fibonacci number. First few Fibonacci numbers are 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 141, ..
Input : 8 Output : Yes Input : 34 Output : Yes Input : 41 Output : No
A simple way is to generate Fibonacci numbers until the generated number is greater than or equal to ‘n’. Following is an interesting property about Fibonacci numbers that can also be used to check if a given number is Fibonacci or not.
A number is Fibonacci if and only if one or both of (5*n2 + 4) or (5*n2 – 4) is a perfect square (Source: Wiki). Following is a simple program based on this concept.
1 is a Fibonacci Number 2 is a Fibonacci Number 3 is a Fibonacci Number 4 is a not Fibonacci Number 5 is a Fibonacci Number 6 is a not Fibonacci Number 7 is a not Fibonacci Number 8 is a Fibonacci Number 9 is a not Fibonacci Number 10 is a not Fibonacci Number
This article is contributed by Abhay Rathi. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above
- Check if a M-th fibonacci number divides N-th fibonacci number
- An efficient way to check whether n-th Fibonacci number is multiple of 10
- Number of ways to represent a number as sum of k fibonacci numbers
- Finding number of digits in n'th Fibonacci number
- Nth Even Fibonacci Number
- Fibonacci number in an array
- n'th multiple of a number in Fibonacci Series
- Count the nodes whose sum with X is a Fibonacci number
- Python Program for n-th Fibonacci number
- Find nth Fibonacci number using Golden ratio
- Program to find last two digits of Nth Fibonacci number
- Distinct pairs from given arrays (a[i], b[j]) such that (a[i] + b[j]) is a Fibonacci number
- C/C++ Program for nth multiple of a number in Fibonacci Series
- Check if a number is divisible by all prime divisors of another number
- Check whether all the rotations of a given number is greater than or equal to the given number or not
Improved By : Mithun Kumar