# How to Check Whether a Number is Fibonacci or Not in Python

Python program to check whether a given number is a fibonacci number or not; Through this tutorial, i am going to show you how to check whether a given number is fibonacci or not in python.

Fibonacci series of numbers is a series of numbers formed by the addition of the preceding two numbers. The term ‘Fibonacci’ for such a sequence of numbers was coined in the 12th century by Leonardo Fibonacci, who was stumbled by the curious problem of a fictional Rabbit’s breeding process.

In this tutorial, i will write a python program to check whether number is fibonacci or not from user input number; as shown below:

```# how to check whether a number is fibonacci or not in python

import math
# function to check perferct square
def checkPerfectSquare(n):
sqrt = int(math.sqrt(n))
if pow(sqrt, 2) == n:
return True
else:
return False
# function to check  Fibonacci number
def isFibonacciNumber(n):
res1 = 5 * n * n + 4
res2 = 5 * n * n - 4
if checkPerfectSquare(res1) or checkPerfectSquare(res2):
return True
else:
return False
# main code
num = int(input("Enter an integer number: "))
# checking
if isFibonacciNumber(num):
print ("Yes,", num, "is a Fibonacci number")
else:
print ("No,", num, "is not a Fibonacci number")```

Output of the above python program to check whether a number is fibonacci or not; as shown below:

```Enter an integer number:  5
Yes, 5 is a Fibonacci number ```