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1 change: 1 addition & 0 deletions project_euler/problem_97/__init__.py
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#
31 changes: 31 additions & 0 deletions project_euler/problem_97/sol1.py
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"""
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 compute_digits(n: int) -> str:
"""
Returns the last n digits of NUMBER.
>>> compute_digits(10)
'8740021009'
>>> compute_digits(-1)
-1
>>> compute_digits(8.3)
-1
"""
if n < 0 or not isinstance(n, int):
return -1
MODULUS = 10 ** n
NUMBER = 28433 * (pow(2, 7830457, MODULUS) + 1)
return str(NUMBER % MODULUS)


if __name__ == "__main__":
print(f"{compute_digits(10)}")