## Using the function

In [1]:

```
n = int(input("Please enter a positive number : "))
def is_Perfect_Square(n):
s = int(n ** 0.5)
return s*s == n
if (is_Perfect_Square(5*n*n+4) or is_Perfect_Square(5*n*n-4)):
print(n, "is fibanacci.")
else:
print(n, "is not fibanacci.")
```

In this program, we ask the user to enter the number and check if (5*n*n+4) or (5*n*n-4) or both are the perfect squares. If any of these is the perfect square, then the number is a Fibonacci number.