""" The first known prime found to exceed one million digits was discovered in 1999, and is a Mersenne prime of the form 2**6972593 − 1; it contains exactly 2,098,960 digits. Subsequently other Mersenne primes, of the form 2**p − 1, have been found which contain more digits. However, in 2004 there was found a massive non-Mersenne prime which contains 2,357,207 digits: (28433 * (2 ** 7830457 + 1)). Find the last ten digits of this prime number. """ def solution(n: int = 10) -> str: """ Returns the last n digits of NUMBER. >>> solution() '8739992577' >>> solution(8) '39992577' >>> solution(1) '7' >>> solution(-1) Traceback (most recent call last): ... ValueError: Invalid input >>> solution(8.3) Traceback (most recent call last): ... ValueError: Invalid input >>> solution("a") Traceback (most recent call last): ... ValueError: Invalid input """ if not isinstance(n, int) or n < 0: raise ValueError("Invalid input") MODULUS = 10**n NUMBER = 28433 * (pow(2, 7830457, MODULUS)) + 1 return str(NUMBER % MODULUS) if __name__ == "__main__": from doctest import testmod testmod() print(f"{solution(10) = }")