#### Fibonacci Number Check

A
```package com.thealgorithms.maths;

/**
* Fibonacci: 0 1 1 2 3 5 8 13 21 ...
* This code checks Fibonacci Numbers up to 45th number.
* Other checks fail because of 'long'-type overflow.
*/
public final class FibonacciNumberCheck {
private FibonacciNumberCheck() {
}
/**
* Check if a number is perfect square number
*
* @param number the number to be checked
* @return <tt>true</tt> if {@code number} is a perfect square, otherwise
*         <tt>false</tt>
*/
public static boolean isPerfectSquare(long number) {
long sqrt = (long) Math.sqrt(number);
return sqrt * sqrt == number;
}

/**
* Check if a number is a Fibonacci number. This is true if and only if at
* least one of 5x^2+4 or 5x^2-4 is a perfect square
*
* @param number the number
* @return <tt>true</tt> if {@code number} is a Fibonacci number, otherwise
*         <tt>false</tt>
*/
public static boolean isFibonacciNumber(long number) {
long value1 = 5 * number * number + 4;
long value2 = 5 * number * number - 4;
return isPerfectSquare(value1) || isPerfectSquare(value2);
}
}
```