How to write a program to check if a number is a Fibonacci number or not, just using import, while, if-else keywords?

Answer 1

In Python I assume?

Way 1 : Using Property / Fast

from math import sqrt
def Square(x): # returns true if perfect square
    s = int(sqrt(x))
    return s*s == x

def Fibonacci(n):
# n is Fibonacci if 5n^2 + 4 or
# 5n^2 - 4 are perfect squares.
return Square(5*n*n + 4) or Square(5*n*n - 4)

Way 2 : Using Loops / Slower (Relatively)

def Fibonacci(n):
f1 = 1, f2 = 1
f3 = 0
for i in range (1,2*n):
f3 = f1 + f2
f1 = f2
f2 = f3
if f3 > n:
break
if f2 != n or f1 != n:
return False
else
return True

Answer 2

Fibonacci numbers are in the divine proportion of 1.6:1 (approx). Use this to make the program...I am not gonna tell everything 😉