Given a Number N check if it part of Fibonacci Series or Not?

I know fibonacci series is fn = f(n-1)+f(n-2) but how to check if a no is part of Fibonacci series or not please tell the logic in detail example

hello @anantgovil123
A simple way is to generate Fibonacci numbers until the generated number is greater than or equal to ā€˜nā€™. 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 (5n^2 + 4) or (5n^2 ā€“ 4) is a perfect square

so just check for above condition .
image