Hi there, I’m having some problems to solve this challenge. I’ve tried working with the phi(n) function (from sympy) to calculate the private exponent (d). However until this moment it haven’t worked because it seems a complicate calculation for large numbers (or I don’t know if I’m using the incorrect function since @Fukurou mentioned that It only need basic math). I would thank if someone could advice me or told me If I’ve forgotten a step to find the solution.