# Large non-Mersenne prime

*Author: Andrei Osipov*

https://projecteuler.net/problem=97

The first known prime found to exceed one million digits was discovered in 1999, and is a Mersenne prime of the form 26972593ā1; it contains exactly 2,098,960 digits. Subsequently other Mersenne primes, of the form 2pā1, have been found which contain more digits.

However, in 2004 there was found a massive non-Mersenne prime which contains 2,357,207 digits: 28433Ć2**7830457+1.

Find the last ten digits of this prime number.

Source code: prob097-andreoss.pl

use v6; sub power-mod($b is copy, $e is copy, $m is copy where $b & $e & $m > 0) { my $r = 1; while $e != 0 { $r = $r * $b mod $m if $e !%% 2; $e = floor $e/2; $b = $b ** 2 mod $m } $r; } say (power-mod(2, 7830457, 10**10) * 28433 + 1) mod 10**10 ;