Inverse Modulo N. Integers modulo n) exists precisely when gcd(a;n) = 1. If we simply rearrange the equation to read ax k n = 1;
Or equivalently, an integer x such that ax = 1 + k n for some k. Integers modulo n) exists precisely when gcd(a;n) = 1. M 1 77 2 (mod5), and hence an inverse to m 1 mod n 1 is y 1 = 3.
It can be shown that such an inverse exists if and only if a and m are coprime, but we will ignore this for this task.
So that (the residue of) y is the multiplicative inverse of b, mod a. For example, let m = 4, a = 2. We should note that the modular inverse does not always exist. Modular multiplicative inverse in python.
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